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2018 Volume 38 Issue 1
2018, 38(1): 1-10
doi: 10.6023/cjoc201708050
Abstract:
The oxime or hydrazone formation is a classic condensation reaction between aldehydes/ketones and hydroxyl amine or hydrazine. It is a simple, yet fundamental coupling reaction that has been widely applied in the ligations and conjugations of biomolecules and material synthesis. However, the reactions are usually sluggish and normally require acidic conditions with large excess of substrates to facilitate conversion, which limit their wide applications. Recent studies have shown that aniline as a nucleophilic catalyst can significantly accelerate the oxime/hydrazone formation reaction, preliminarily solving the reaction rate issue under mild and bio-compatible conditions. Therefore, it has been the most common coupling method in the modification of biological macromolecules. In this review, the design and development of aromatic amine catalyst in recent years as well as the catalytic mechanism and structure activity relationship are summarized. The application of highly active aniline catalysis in bioconjugations and material synthesis was also included together with a prospect for future development.
The oxime or hydrazone formation is a classic condensation reaction between aldehydes/ketones and hydroxyl amine or hydrazine. It is a simple, yet fundamental coupling reaction that has been widely applied in the ligations and conjugations of biomolecules and material synthesis. However, the reactions are usually sluggish and normally require acidic conditions with large excess of substrates to facilitate conversion, which limit their wide applications. Recent studies have shown that aniline as a nucleophilic catalyst can significantly accelerate the oxime/hydrazone formation reaction, preliminarily solving the reaction rate issue under mild and bio-compatible conditions. Therefore, it has been the most common coupling method in the modification of biological macromolecules. In this review, the design and development of aromatic amine catalyst in recent years as well as the catalytic mechanism and structure activity relationship are summarized. The application of highly active aniline catalysis in bioconjugations and material synthesis was also included together with a prospect for future development.
2018, 38(1): 11-28
doi: 10.6023/cjoc201709009
Abstract:
Aromaticity is one of the most fundamental concept in organic chemistry. Aromatic compounds generally present special thermodynamic stability. Research on aromaticity can help us to understand the stability essence of aromatic compounds, and thus enables the further prediction and construction of species with stabilization or destablization. The endless richness of aromaticity researches usually originates the nature and criterion of aromaticity. The main emphasis of this review is on a discussion of historical discoveries, definitions and classification of aromaticity-related structural types, as well as various theoretically and experimentally criterions. Furthermore, this review contains the recent development of aromaticity illustrated by recent representative examples.
Aromaticity is one of the most fundamental concept in organic chemistry. Aromatic compounds generally present special thermodynamic stability. Research on aromaticity can help us to understand the stability essence of aromatic compounds, and thus enables the further prediction and construction of species with stabilization or destablization. The endless richness of aromaticity researches usually originates the nature and criterion of aromaticity. The main emphasis of this review is on a discussion of historical discoveries, definitions and classification of aromaticity-related structural types, as well as various theoretically and experimentally criterions. Furthermore, this review contains the recent development of aromaticity illustrated by recent representative examples.
2018, 38(1): 29-39
doi: 10.6023/cjoc201708065
Abstract:
Insulin is a commonly prescribed drug for the treatment of type Ⅰ and type Ⅱ diabetes. As for the efficiency in controlling blood glucose level, insulin therapy is one of the most effective treatments for diabetes. The current administration route of insulin is mainly through subcutaneous injection, which leads to many undesirable side effects such as pain, local tissue necrosis or infection, and nerve damage. Recently, various closed-loop and smart insulin delivery systems have been developed based on the emerging nanotechnologies. Recent progress in the construction of closed-loop and smart insulin delivery system, which mainly focuses on the response mechanism, different strategies for fabricating the carrier matrix, and the regulation principle of the smart insulin release is described. Advantages and drawbacks of the current insulin delivery systems are also discussed, along with the opportunities and challenges in future.
Insulin is a commonly prescribed drug for the treatment of type Ⅰ and type Ⅱ diabetes. As for the efficiency in controlling blood glucose level, insulin therapy is one of the most effective treatments for diabetes. The current administration route of insulin is mainly through subcutaneous injection, which leads to many undesirable side effects such as pain, local tissue necrosis or infection, and nerve damage. Recently, various closed-loop and smart insulin delivery systems have been developed based on the emerging nanotechnologies. Recent progress in the construction of closed-loop and smart insulin delivery system, which mainly focuses on the response mechanism, different strategies for fabricating the carrier matrix, and the regulation principle of the smart insulin release is described. Advantages and drawbacks of the current insulin delivery systems are also discussed, along with the opportunities and challenges in future.
2018, 38(1): 51-61
doi: 10.6023/cjoc201708030
Abstract:
Ferrocenes bearing planar chirality have been demonstrated to be highly efficient ligands or catalysts in asymmetric catalysis. In view of their atom and step economies, direct asymmetric C—H bond functionalization is the most concise and powerful method for the construction of planar chiral ferrocenes compared with traditional approaches. This review summarizes recent progress on the development of novel methods to synthesize planar chiral compounds via transition-metal (Cu-, Pd-, Ir-, Rh-, Au-, Pt-) catalyzed asymmetric C—H bond functionalization. Preparation of a variety of new planar chiral ferrocene-based catalysts and ligands by utilizing these methods and their application in catalytic asymmetric reactions are also discussed.
Ferrocenes bearing planar chirality have been demonstrated to be highly efficient ligands or catalysts in asymmetric catalysis. In view of their atom and step economies, direct asymmetric C—H bond functionalization is the most concise and powerful method for the construction of planar chiral ferrocenes compared with traditional approaches. This review summarizes recent progress on the development of novel methods to synthesize planar chiral compounds via transition-metal (Cu-, Pd-, Ir-, Rh-, Au-, Pt-) catalyzed asymmetric C—H bond functionalization. Preparation of a variety of new planar chiral ferrocene-based catalysts and ligands by utilizing these methods and their application in catalytic asymmetric reactions are also discussed.
2018, 38(1): 62-74
doi: 10.6023/cjoc201708023
Abstract:
The scientists have been working on developing more efficient and green ways to synthesize organophosphorus compounds as they have broad utilities such as reagents for chemical reactions, photovoltaic materials, flame retardants, biologically active molecules and so on. The difunctionalization reactions between P-center radicals and unsaturated compounds provide powerful methods for the synthesis of organophosphorus compounds in least and concise steps. This review will summarize the recent development in this area on the basis of different types of P-centered radical initiators.
The scientists have been working on developing more efficient and green ways to synthesize organophosphorus compounds as they have broad utilities such as reagents for chemical reactions, photovoltaic materials, flame retardants, biologically active molecules and so on. The difunctionalization reactions between P-center radicals and unsaturated compounds provide powerful methods for the synthesis of organophosphorus compounds in least and concise steps. This review will summarize the recent development in this area on the basis of different types of P-centered radical initiators.
2018, 38(1): 40-50
doi: 10.6023/cjoc201708006
Abstract:
Iron-catalyzed cross-coupling reactions between organometallic nucleophiles and organic halides as electrophiles represent one of the most powerful methods in the field of carbon-carbon bond construction. This review is concerned with the additive effect in iron-catalyzed cross-coupling reactions of Grignard reagents, whose results were published in recent years.
Iron-catalyzed cross-coupling reactions between organometallic nucleophiles and organic halides as electrophiles represent one of the most powerful methods in the field of carbon-carbon bond construction. This review is concerned with the additive effect in iron-catalyzed cross-coupling reactions of Grignard reagents, whose results were published in recent years.
2018, 38(1): 75-85
doi: 10.6023/cjoc201707019
Abstract:
Progress in the synthesis and application of the cyclopalladated derivatives of ferrocene with a donor nitrogen atom in the directing group is surveyed including the planar chirality and enantioselective catalysis of organic reactions and rearrangements. Transannular palladation has been found giving achiral 1, 1'-disubstituted ferrocenes of ansa-structure. Cyclopalladated ferrocenes have been widely used as catalysts in the cross-coupling reactions (Suzuki, Heck, aza-Claisen, etc.)
Progress in the synthesis and application of the cyclopalladated derivatives of ferrocene with a donor nitrogen atom in the directing group is surveyed including the planar chirality and enantioselective catalysis of organic reactions and rearrangements. Transannular palladation has been found giving achiral 1, 1'-disubstituted ferrocenes of ansa-structure. Cyclopalladated ferrocenes have been widely used as catalysts in the cross-coupling reactions (Suzuki, Heck, aza-Claisen, etc.)
2018, 38(1): 86-94
doi: 10.6023/cjoc201708049
Abstract:
A simple and mild protocol for the copper-catalyzed decarboxylative coupling of alkenyl acids with P(O)H compounds was developed, thus providing a facile route to the vinylphosphorus compounds. Moreover, the reaction could also afford β-ketophosphorus compounds as the major products in air using oxygen as an oxidant. In addition, the remarkable features of these two types of reactions include excellent reaction chemoselectivity, good functional group tolerance and mild reaction conditions (e.g., cheap oxidant, ligand-free condition and room temperature).
A simple and mild protocol for the copper-catalyzed decarboxylative coupling of alkenyl acids with P(O)H compounds was developed, thus providing a facile route to the vinylphosphorus compounds. Moreover, the reaction could also afford β-ketophosphorus compounds as the major products in air using oxygen as an oxidant. In addition, the remarkable features of these two types of reactions include excellent reaction chemoselectivity, good functional group tolerance and mild reaction conditions (e.g., cheap oxidant, ligand-free condition and room temperature).
2018, 38(1): 95-102
doi: 10.6023/cjoc201710029
Abstract:
An efficient and practical protocol for palladium-catalyzed direct C—H bond arylation of imidazo[1, 2-a]pyridines with cheap aryl/heteroaryl chlorides has been developed. Various imidazo[1, 2-a]pyridines with electron-neutral, electron-poor, electron-rich, even sterically hindered aryl chlorides and heteroaryl chlorides were successfully applied to the reaction in aqueous medium to achieve the 3-arylimidazo[1, 2-a]pyridines in mostly good to excellent yields, thus representing a signifi-cant advancement in the implementation of the direct C—H bond arylation of imidazo[1, 2-a]pyridines with aryl chlorides.
An efficient and practical protocol for palladium-catalyzed direct C—H bond arylation of imidazo[1, 2-a]pyridines with cheap aryl/heteroaryl chlorides has been developed. Various imidazo[1, 2-a]pyridines with electron-neutral, electron-poor, electron-rich, even sterically hindered aryl chlorides and heteroaryl chlorides were successfully applied to the reaction in aqueous medium to achieve the 3-arylimidazo[1, 2-a]pyridines in mostly good to excellent yields, thus representing a signifi-cant advancement in the implementation of the direct C—H bond arylation of imidazo[1, 2-a]pyridines with aryl chlorides.
2018, 38(1): 112-117
doi: 10.6023/cjoc201711001
Abstract:
The monofluoromethylation of purin-9-yl allenes with fluorobis(phenylsulfonyl)methane has been achieved. With AgF (3 mol%) as the catalyst, the fluorobis(phenylsulfonyl)methylated adducts could be afforded in excellent yields. The monofluoromethylation exhibited high chemoselectivities and E-selectivies. Meanwhile, the monofluoromethylation of purin-9-yl allenes with fluorobis(phenylsulfonyl)methane provided a useful route to construct fluorinated acyclic nucleoside analogues.
The monofluoromethylation of purin-9-yl allenes with fluorobis(phenylsulfonyl)methane has been achieved. With AgF (3 mol%) as the catalyst, the fluorobis(phenylsulfonyl)methylated adducts could be afforded in excellent yields. The monofluoromethylation exhibited high chemoselectivities and E-selectivies. Meanwhile, the monofluoromethylation of purin-9-yl allenes with fluorobis(phenylsulfonyl)methane provided a useful route to construct fluorinated acyclic nucleoside analogues.
2018, 38(1): 118-123
doi: 10.6023/cjoc201708037
Abstract:
A serial of biphenyl bisimidazolines containing both axial and central chirality have been synthesized for the first time. Compared with common method, Ullmann coupling methodology exhibited superior performance expecially for t-Bu substituted ligands. The obtained ligands were further applied in the Cu-catalyzed asymmetric cyclopropanation.
A serial of biphenyl bisimidazolines containing both axial and central chirality have been synthesized for the first time. Compared with common method, Ullmann coupling methodology exhibited superior performance expecially for t-Bu substituted ligands. The obtained ligands were further applied in the Cu-catalyzed asymmetric cyclopropanation.
2018, 38(1): 124-130
doi: 10.6023/cjoc201709054
Abstract:
A novel and simple protocol has been developed for the regioselective sulfonylation of quinolone N-oxides at their C-2 postition. This method features with a simple system, high efficiency, environmental friendliness, and metal-free conditions. Aliphatic and aryl sulfonyl hydrazides smoothly undergo sulfonylation with quinoline N-oxides in good yields.
A novel and simple protocol has been developed for the regioselective sulfonylation of quinolone N-oxides at their C-2 postition. This method features with a simple system, high efficiency, environmental friendliness, and metal-free conditions. Aliphatic and aryl sulfonyl hydrazides smoothly undergo sulfonylation with quinoline N-oxides in good yields.
2018, 38(1): 138-147
doi: 10.6023/cjoc201708005
Abstract:
Two orthorganally protected 3'-azido-3'-deoxy-D/L-ribosides were synthesized and successfully glycosylated with various pyrimidine, pyridine and purine related heterocyclic bases. 3'-Azido-3'-deoxy-D-pyrimidine nucleosides, purine nucleosides as well as 3'-azido-3'-deoxy-L-nucleosides were synthesized. 3'-Azido-3'-deoxy-6-azauridine, 4-deoxyuridine, 2-thiouridine, 3-deazauridine, nitropyridinone and isocytidine derivatives were also synthesized as the drug analogues to explore their biological properties. 14 final products are novel and well characterized, while all of the 31 final products were synthesized by the new strategy from the corresponding novel key intermediates. The two key intermediates can be utilized to make all kinds of novel nucleoside derivatives by glycosylating with various heterocyclic bases.
Two orthorganally protected 3'-azido-3'-deoxy-D/L-ribosides were synthesized and successfully glycosylated with various pyrimidine, pyridine and purine related heterocyclic bases. 3'-Azido-3'-deoxy-D-pyrimidine nucleosides, purine nucleosides as well as 3'-azido-3'-deoxy-L-nucleosides were synthesized. 3'-Azido-3'-deoxy-6-azauridine, 4-deoxyuridine, 2-thiouridine, 3-deazauridine, nitropyridinone and isocytidine derivatives were also synthesized as the drug analogues to explore their biological properties. 14 final products are novel and well characterized, while all of the 31 final products were synthesized by the new strategy from the corresponding novel key intermediates. The two key intermediates can be utilized to make all kinds of novel nucleoside derivatives by glycosylating with various heterocyclic bases.
2018, 38(1): 103-111
doi: 10.6023/cjoc201709047
Abstract:
A series of conjugated compounds containing imidazole structure units were designed and synthesized. Their structures were characterized by 1H NMR, 13C NMR, MS and elemental analysis. Their UV absorption wavelength (λa), fluorescence emission wavelength (λe), fluorescence quantum yield (Φ) and fluorescence lifetime (τ) were determined, and the relationships between the molecular structures and its spectral data were discussed. The results showed that these compounds possess strong luminescence characteristic, and the maximum value of Φ is 91%. 1, 4-Bis-(2-(1-benzylbenzimidazole))benzene (5b) was selected to fabricate organic light-emitting diode (OLED). Its main luminous peak is at 448 nm, the maximum brightness is 6790 cd•m－2 when the voltage is 23.8 V (875 mA•cm－2), the maximum current efficiency is 1.17 cd•A－1, the maximum power efficiency is 0.96 lm•W－1, and the maximum external quantum efficiency is 0.92%, which indicate that these compounds have great potential application value as OLED materials.
A series of conjugated compounds containing imidazole structure units were designed and synthesized. Their structures were characterized by 1H NMR, 13C NMR, MS and elemental analysis. Their UV absorption wavelength (λa), fluorescence emission wavelength (λe), fluorescence quantum yield (Φ) and fluorescence lifetime (τ) were determined, and the relationships between the molecular structures and its spectral data were discussed. The results showed that these compounds possess strong luminescence characteristic, and the maximum value of Φ is 91%. 1, 4-Bis-(2-(1-benzylbenzimidazole))benzene (5b) was selected to fabricate organic light-emitting diode (OLED). Its main luminous peak is at 448 nm, the maximum brightness is 6790 cd•m－2 when the voltage is 23.8 V (875 mA•cm－2), the maximum current efficiency is 1.17 cd•A－1, the maximum power efficiency is 0.96 lm•W－1, and the maximum external quantum efficiency is 0.92%, which indicate that these compounds have great potential application value as OLED materials.
2018, 38(1): 131-137
doi: 10.6023/cjoc201710022
Abstract:
β-Amino-carbonyl fragments are important structures of many bioactive molecules and pharmaceuticals and critical synthetic blocks which can be easily converted into other structures and compounds. A novel method for preparing β-amino-carbonyl compounds with oxygen as an oxidant, palladium acetate and cuprous chloride as catalysts was reported. The chiral high allyl amine compounds can be converted into corresponding β-amino carbonyl compounds with moderate to good yield, good substrate scope, and tolerance of chiral centers. Natural product (+)-sedridine was synthesized with 32% yield.
β-Amino-carbonyl fragments are important structures of many bioactive molecules and pharmaceuticals and critical synthetic blocks which can be easily converted into other structures and compounds. A novel method for preparing β-amino-carbonyl compounds with oxygen as an oxidant, palladium acetate and cuprous chloride as catalysts was reported. The chiral high allyl amine compounds can be converted into corresponding β-amino carbonyl compounds with moderate to good yield, good substrate scope, and tolerance of chiral centers. Natural product (+)-sedridine was synthesized with 32% yield.
2018, 38(1): 148-155
doi: 10.6023/cjoc201708042
Abstract:
Four novel cationic antibacterial peptide analogs were modified at the N-terminus of the cell-penetrating peptide transacting activator of transcription TAT(49-57) by attaching dipeptides. Peptides were synthesized through standard Fmoc solid-phase peptide synthesis procedures, purified by reversed-phase high performance liquid chromatography (RP-HPLC), and characterized by 1H NMR, ESI-MS and elemental analysis. Tat(YY), Tat(FF), Tat(FF) and Tat(YY), Tat(FF) demonstrated better antibacterial activities against E. coli, S. typhimurium, B. subtilis and S. aureus with low hemolysis. respectively, but had no inhibitory effect on fungus growth. The Tat(49-57) analogs inhibited the bacteria more effectively than Tat(49-57). The interactions between peptides and calf thymus DNA (ct-DNA) were investigated with multi-spectroscopic techniques. The results showed that both peptides could interact with DNA via the groove binding mode. Compared to TAT(49-57), antibacterial peptide analogs combined with DNA much closer via binding constants, which has the value to become an excellent antibacterial agent with further improved and designed.
Four novel cationic antibacterial peptide analogs were modified at the N-terminus of the cell-penetrating peptide transacting activator of transcription TAT(49-57) by attaching dipeptides. Peptides were synthesized through standard Fmoc solid-phase peptide synthesis procedures, purified by reversed-phase high performance liquid chromatography (RP-HPLC), and characterized by 1H NMR, ESI-MS and elemental analysis. Tat(YY), Tat(FF), Tat(FF) and Tat(YY), Tat(FF) demonstrated better antibacterial activities against E. coli, S. typhimurium, B. subtilis and S. aureus with low hemolysis. respectively, but had no inhibitory effect on fungus growth. The Tat(49-57) analogs inhibited the bacteria more effectively than Tat(49-57). The interactions between peptides and calf thymus DNA (ct-DNA) were investigated with multi-spectroscopic techniques. The results showed that both peptides could interact with DNA via the groove binding mode. Compared to TAT(49-57), antibacterial peptide analogs combined with DNA much closer via binding constants, which has the value to become an excellent antibacterial agent with further improved and designed.
2018, 38(1): 156-161
doi: 10.6023/cjoc201708060
Abstract:
The efficient total synthesis of cudratricusxanthone B (1), a biologically interesting natural isoprenylated xanthone, has been achieved for the first time starting from commercially available 2, 4-dihydroxybenzoic acid via a linear reaction sequence of 8 steps with the overall yield of 3.1%, wherein Claisen rearrangement and demethylation with AlCl3/pyridine are used as key reactions. This work definitely laid the foundation for the further pharmacological study of this natural compound. Meanwhile, another xanthone (2) has been synthesized, which proved the reported structure of the natural xanthone staudtiixanthone D to be wrong.
The efficient total synthesis of cudratricusxanthone B (1), a biologically interesting natural isoprenylated xanthone, has been achieved for the first time starting from commercially available 2, 4-dihydroxybenzoic acid via a linear reaction sequence of 8 steps with the overall yield of 3.1%, wherein Claisen rearrangement and demethylation with AlCl3/pyridine are used as key reactions. This work definitely laid the foundation for the further pharmacological study of this natural compound. Meanwhile, another xanthone (2) has been synthesized, which proved the reported structure of the natural xanthone staudtiixanthone D to be wrong.
2018, 38(1): 183-189
doi: 10.6023/cjoc201706025
Abstract:
The asymmetric Michael addition reaction of α, α-disubstituted aldehydes to maleimides catalyzed by new bifunctional primary amine-squaramides has been developed. This organocatalytic asymmetric reaction provides easy access to functionalized succinimides with a broad substrate scope. Both enantiomers of desired succinimide derivatives were obtained in good to excellent yields (up to 98%) with excellent enantioselectivities (up to >99% ee)
The asymmetric Michael addition reaction of α, α-disubstituted aldehydes to maleimides catalyzed by new bifunctional primary amine-squaramides has been developed. This organocatalytic asymmetric reaction provides easy access to functionalized succinimides with a broad substrate scope. Both enantiomers of desired succinimide derivatives were obtained in good to excellent yields (up to 98%) with excellent enantioselectivities (up to >99% ee)
2018, 38(1): 190-199
doi: 10.6023/cjoc201708046
Abstract:
A gold-catalyzed oxidative ring expansion of 1-alkynyl-1, 2-dihydrophthalazines has been developed. The reaction was catalyzed by PPh3AuNTf2in the presence of 8-methylquinoline N-oxide as the oxidant, leading to 2, 3-benzodiazepine derivatives with high efficiency. The reaction likely proceeds through the formation of α-carbonyl gold carbene and 1, 2-migration of a phenyl group, while no 1, 2-H and 1, 2-N migration take place. Further transformation of 2, 3-benzodiazepine products in the presence of FeCl3 was also carried out, pyrazole and polyfused heterocycle were formed, respectively, through variation of the amounts of FeCl3.
A gold-catalyzed oxidative ring expansion of 1-alkynyl-1, 2-dihydrophthalazines has been developed. The reaction was catalyzed by PPh3AuNTf2in the presence of 8-methylquinoline N-oxide as the oxidant, leading to 2, 3-benzodiazepine derivatives with high efficiency. The reaction likely proceeds through the formation of α-carbonyl gold carbene and 1, 2-migration of a phenyl group, while no 1, 2-H and 1, 2-N migration take place. Further transformation of 2, 3-benzodiazepine products in the presence of FeCl3 was also carried out, pyrazole and polyfused heterocycle were formed, respectively, through variation of the amounts of FeCl3.
2018, 38(1): 215-220
doi: 10.6023/cjoc201708009
Abstract:
A concise and efficient iodine/copper(Ⅰ) iodide-mediated intramolecular oxidative C—O bond formation reaction has been developed for oxazole synthesis. Under the optimal reaction conditions, oxidative cyclization of readily accessible enamide substrates provides facile access to a variety of oxazole derivatives bearing aryl, alkyl, amide, ester, and acyl substituents.
A concise and efficient iodine/copper(Ⅰ) iodide-mediated intramolecular oxidative C—O bond formation reaction has been developed for oxazole synthesis. Under the optimal reaction conditions, oxidative cyclization of readily accessible enamide substrates provides facile access to a variety of oxazole derivatives bearing aryl, alkyl, amide, ester, and acyl substituents.
2018, 38(1): 221-227
doi: 10.6023/cjoc201708002
Abstract:
As a characteristic structural motif of numerous biologically active natural products and new drugs, chiral indoline derivatives have attracted much attention of chemists. Although many methods are available, there is still great need to develop a new, simple and highly efficient asymmetric synthetic method of indoline derivatives. Starting from Williams chiral auxiliary, a variety of methyl (R)-N-(tert-butoxycarbonyl)indoline-2-carboxylates were obtained with high overall yields and enantioselectivity through nucleophilic substitution, intramolecular Buchwald-Hartwig coupling reaction, etc.
As a characteristic structural motif of numerous biologically active natural products and new drugs, chiral indoline derivatives have attracted much attention of chemists. Although many methods are available, there is still great need to develop a new, simple and highly efficient asymmetric synthetic method of indoline derivatives. Starting from Williams chiral auxiliary, a variety of methyl (R)-N-(tert-butoxycarbonyl)indoline-2-carboxylates were obtained with high overall yields and enantioselectivity through nucleophilic substitution, intramolecular Buchwald-Hartwig coupling reaction, etc.
2018, 38(1): 162-170
doi: 10.6023/cjoc201708066
Abstract:
A detailed logic-guided approach towards chiral ligands design is described via the enantioselective analysis of the dynamic conformational behaviors of catalyst, which is based on a mathematical relationship between conformations and enantioselectivity, for asymmetric addition of diethylzinc to benzaldehyde. Following this logic thought, 94 examples, almost all highly enantioselective β-aminoalcohol ligands reported, can be rationally devised by the logic control of the dynamic conformational behaviors of the catalyst from the simplest β-aminoalcohol with one single chiral center as starting point.
A detailed logic-guided approach towards chiral ligands design is described via the enantioselective analysis of the dynamic conformational behaviors of catalyst, which is based on a mathematical relationship between conformations and enantioselectivity, for asymmetric addition of diethylzinc to benzaldehyde. Following this logic thought, 94 examples, almost all highly enantioselective β-aminoalcohol ligands reported, can be rationally devised by the logic control of the dynamic conformational behaviors of the catalyst from the simplest β-aminoalcohol with one single chiral center as starting point.
2018, 38(1): 171-182
doi: 10.6023/cjoc201709010
Abstract:
Two series of platinum complexes, 1a~6a and 1b-6b, based on tridentate cyclometalating ligands 2-aryl-6-(1H-pyrazol-1-yl)pyridine [Ar＝phenyl (L1), 2, 4-difluorophenyl (L2), 3, 5-dimethylphenyl (L3), 3-methoxyphenyl (L4), 2-thienyl (L5), 2-benzothienyl (L6)], and phenylethynyl and phenyl ancillary ligand were synthesized and characterized. The X-ray crystal structures of 2b, 3b and 5b were determined, which revealed a twisted orientation of the phenyl ligand with respect to the coordination plane and a weaker Pt—C(phenyl) bond compared with the Pt—C(alkynyl) bond in 1a. Photophysical properties including electronic absorption and emission spectra were studied. Complexes 1a~6a based on the phenylethynyl ligand were strongly emissive, while 1b~3b based on the phenyl ligand were only weakly emissive. However, 4b~6b displayed lower but decent photoluminescent quantum yields than those of 4a~6a, which is explained by the localization of the excited states in the tridentate cyclometalating ligands. The higher quantum efficiencies displayed by the complexes 1a~6a may be attributed to the stronger and more rigid acetylide ligand.
Two series of platinum complexes, 1a~6a and 1b-6b, based on tridentate cyclometalating ligands 2-aryl-6-(1H-pyrazol-1-yl)pyridine [Ar＝phenyl (L1), 2, 4-difluorophenyl (L2), 3, 5-dimethylphenyl (L3), 3-methoxyphenyl (L4), 2-thienyl (L5), 2-benzothienyl (L6)], and phenylethynyl and phenyl ancillary ligand were synthesized and characterized. The X-ray crystal structures of 2b, 3b and 5b were determined, which revealed a twisted orientation of the phenyl ligand with respect to the coordination plane and a weaker Pt—C(phenyl) bond compared with the Pt—C(alkynyl) bond in 1a. Photophysical properties including electronic absorption and emission spectra were studied. Complexes 1a~6a based on the phenylethynyl ligand were strongly emissive, while 1b~3b based on the phenyl ligand were only weakly emissive. However, 4b~6b displayed lower but decent photoluminescent quantum yields than those of 4a~6a, which is explained by the localization of the excited states in the tridentate cyclometalating ligands. The higher quantum efficiencies displayed by the complexes 1a~6a may be attributed to the stronger and more rigid acetylide ligand.
2018, 38(1): 200-207
doi: 10.6023/cjoc201708063
Abstract:
A series of bis(alkoxo)palladium complexes (2 mol%) based on pyridine-containing alcohol ligand were tested for Fujiwara-Moritani reaction of thiophenes/furans with various olefins. The desired products were isolated in moderate to excellent yields under mild conditions. A possible concerted metalation-deprotonation (CMD) pathway for this transformation was proved by control experiments and ESI(+)-MS analysis.
A series of bis(alkoxo)palladium complexes (2 mol%) based on pyridine-containing alcohol ligand were tested for Fujiwara-Moritani reaction of thiophenes/furans with various olefins. The desired products were isolated in moderate to excellent yields under mild conditions. A possible concerted metalation-deprotonation (CMD) pathway for this transformation was proved by control experiments and ESI(+)-MS analysis.
2018, 38(1): 208-214
doi: 10.6023/cjoc201706030
Abstract:
The one-pot one-step synthetic method of 4H-3, 1-benzoxazin-4-ones via the gold-catalyzed oxidative rearrangement of 2-alkynyl arylazides has been developed. The desired products were obtained in moderate to excellent yields under mild reaction conditions. In most cases, using acetic acid as solvent the reactions were shown to proceed very fast within 1 h.
The one-pot one-step synthetic method of 4H-3, 1-benzoxazin-4-ones via the gold-catalyzed oxidative rearrangement of 2-alkynyl arylazides has been developed. The desired products were obtained in moderate to excellent yields under mild reaction conditions. In most cases, using acetic acid as solvent the reactions were shown to proceed very fast within 1 h.
2018, 38(1): 228-236
doi: 10.6023/cjoc201706026
Abstract:
Recently, ternary organic solar cells have emerged as a promising strategy to achieve both high performance and fabrication simplicity for organic solar cells. It has been proved that this strategy is an effective way to achieve improved short-circuit current density (Jsc) with complementary absorption or to get enhanced open-circuit voltage (Voc) through forming energy level cascade. In this work, we designed and synthesized a thieno[3, 2-b]thiphene-substituted porphyrin molecule flanked with two diketopyrrolopyrrole units by ethynylene bridges, named DEP-TT, which exhibited a very low energy bandgap of 1.31 eV and a broad light absorption to 898 nm. The power conversion efficiency (PCE) of binary devices based on DEP-TT and the acceptor [6, 6]-phenyl-C71-butyric-acid-methyl-ester (PC71BM) achieved 7.46% with a relatively low Voc of 0.75 V. Futhermore, the ternary solar cells with 10% indene-C60 bis-adduct (ICBA) achieved high PCE of 8.15%, with higher Voc, Jsc and a relatively higher PCE based on organic solar cells with a porphyrin-small molecule as the donor. This improved performance is believed to be due to the energy level cascade and synergistic effects of the two acceptors of PCBM and ICBA, which suggestes that the ternary bulk heterojunction (BHJ) strategy is a promising way to improve both Voc and Jsc simultaneously and thus overall performance for the same donor material.
Recently, ternary organic solar cells have emerged as a promising strategy to achieve both high performance and fabrication simplicity for organic solar cells. It has been proved that this strategy is an effective way to achieve improved short-circuit current density (Jsc) with complementary absorption or to get enhanced open-circuit voltage (Voc) through forming energy level cascade. In this work, we designed and synthesized a thieno[3, 2-b]thiphene-substituted porphyrin molecule flanked with two diketopyrrolopyrrole units by ethynylene bridges, named DEP-TT, which exhibited a very low energy bandgap of 1.31 eV and a broad light absorption to 898 nm. The power conversion efficiency (PCE) of binary devices based on DEP-TT and the acceptor [6, 6]-phenyl-C71-butyric-acid-methyl-ester (PC71BM) achieved 7.46% with a relatively low Voc of 0.75 V. Futhermore, the ternary solar cells with 10% indene-C60 bis-adduct (ICBA) achieved high PCE of 8.15%, with higher Voc, Jsc and a relatively higher PCE based on organic solar cells with a porphyrin-small molecule as the donor. This improved performance is believed to be due to the energy level cascade and synergistic effects of the two acceptors of PCBM and ICBA, which suggestes that the ternary bulk heterojunction (BHJ) strategy is a promising way to improve both Voc and Jsc simultaneously and thus overall performance for the same donor material.
2018, 38(1): 237-245
doi: 10.6023/cjoc201706027
Abstract:
An intramolecular dinuclear zinc complex was used in asymmetric Friedel-Crafts alkylation of pyrrole with a wide range of chalcone derivatives. This dinuclear zinc complex was prepared in situ by reacting the chiral ligand (S, S)-1 with 2 equiv. of ZnEt2. A series of β-pyrrole-substituted dihydrochalcones were formed mostly in excellent yields (up to 99%) and excellent enantioselectivities (up to >99% ee) by using 15 mol% catalyst loading under mild conditions. A possible mechanism was proposed to explain the origin of the asymmetric induction.
An intramolecular dinuclear zinc complex was used in asymmetric Friedel-Crafts alkylation of pyrrole with a wide range of chalcone derivatives. This dinuclear zinc complex was prepared in situ by reacting the chiral ligand (S, S)-1 with 2 equiv. of ZnEt2. A series of β-pyrrole-substituted dihydrochalcones were formed mostly in excellent yields (up to 99%) and excellent enantioselectivities (up to >99% ee) by using 15 mol% catalyst loading under mild conditions. A possible mechanism was proposed to explain the origin of the asymmetric induction.
2018, 38(1): 246-252
doi: 10.6023/cjoc201708041
Abstract:
Peptide breast cancer susceptibility gene BRCA1 plays an active role in inhibiting female breast cancer. The interaction between BRCA1 and breast cancer suppressor gene protein RAD51 in cancer cell is also an essential part for the treatment of breast cancer. Discovery Studio simulation of the docking process of BRCA1 analogs and RAD51 was used to screen the BRCA1 analogs with different charge and acid-base properties. The R-DOCK evaluation system is used to screened out 4 higher BRCA1 like peptides from the results, and the interactions with BRCA1 analogs of RAD51 peptides (Pep158-180, Pep181-200 and Pep241-260) were studied by using fluorescence spectroscopy and CD spectroscopy. The results indicate that acid-base properties of BRCA1 analogs have great influence on their interaction. The results showed that the effect of BRCA1-3 to RAD51 (Pep158-180/Pep241-260) which is the two key peptides were obviously higher than the other parent peptide. Besides, compared with BRCA1, all BRCA1 analogs combined with RAD51 much closer. The results provide evidence to design novel breast drugs for breast cancer.
Peptide breast cancer susceptibility gene BRCA1 plays an active role in inhibiting female breast cancer. The interaction between BRCA1 and breast cancer suppressor gene protein RAD51 in cancer cell is also an essential part for the treatment of breast cancer. Discovery Studio simulation of the docking process of BRCA1 analogs and RAD51 was used to screen the BRCA1 analogs with different charge and acid-base properties. The R-DOCK evaluation system is used to screened out 4 higher BRCA1 like peptides from the results, and the interactions with BRCA1 analogs of RAD51 peptides (Pep158-180, Pep181-200 and Pep241-260) were studied by using fluorescence spectroscopy and CD spectroscopy. The results indicate that acid-base properties of BRCA1 analogs have great influence on their interaction. The results showed that the effect of BRCA1-3 to RAD51 (Pep158-180/Pep241-260) which is the two key peptides were obviously higher than the other parent peptide. Besides, compared with BRCA1, all BRCA1 analogs combined with RAD51 much closer. The results provide evidence to design novel breast drugs for breast cancer.
2018, 38(1): 253-258
doi: 10.6023/cjoc201708052
Abstract:
4, 5-Diazafluoren-9-one (2), 4, 5-diazafluorene (3) and 9-methylene-4, 5-diazafluorene (5) were prepared by 1, 10-Phenanthroline (1) as starting material. Using n-butyllithium to react with 3 (or using methyllithium to react with 5), the corresponding organic lithium salts could be given, and then, the optically active epichlorohydrin (ECH, ee>98%) was added dropwise at －50 ℃, according to regular treatment, the optically pure terminal epoxides (4 and 6) with diazafluorenyl substituent were obtained. The ee values of epoxides are larger than 98%. Using ethylmagnesium bromide (or phenylmagnesium bromide) to react with 2 in the presence of potassium hydroxide and tetrabutylammonium bromide, the corresponding substituted epoxy compounds (8a and 8b) were produced. The ee values of epoxides (8a and 8b) are larger than 97%. The epoxides (4, 6, 8a and 8b) were polymerized using KOH as an initiator and the polyethers with narrow molecular weight distributions (Mw/Mn＝1.04 to 1.10) were obtained. The products were analyzed by NMR, elemental analysis and GPC.
4, 5-Diazafluoren-9-one (2), 4, 5-diazafluorene (3) and 9-methylene-4, 5-diazafluorene (5) were prepared by 1, 10-Phenanthroline (1) as starting material. Using n-butyllithium to react with 3 (or using methyllithium to react with 5), the corresponding organic lithium salts could be given, and then, the optically active epichlorohydrin (ECH, ee>98%) was added dropwise at －50 ℃, according to regular treatment, the optically pure terminal epoxides (4 and 6) with diazafluorenyl substituent were obtained. The ee values of epoxides are larger than 98%. Using ethylmagnesium bromide (or phenylmagnesium bromide) to react with 2 in the presence of potassium hydroxide and tetrabutylammonium bromide, the corresponding substituted epoxy compounds (8a and 8b) were produced. The ee values of epoxides (8a and 8b) are larger than 97%. The epoxides (4, 6, 8a and 8b) were polymerized using KOH as an initiator and the polyethers with narrow molecular weight distributions (Mw/Mn＝1.04 to 1.10) were obtained. The products were analyzed by NMR, elemental analysis and GPC.
2018, 38(1): 259-265
doi: 10.6023/cjoc201708036
Abstract:
The trinuclear N-heterocyclic carbene-palladium(Ⅱ) complexes were found to be the effective catalyst precursors for the Buchwald-Hartwig amination of aryl chlorides. With catalyst loading of 2.0 mol%, the amination of secondary and primary amines with a variety of electronically and structurally diverse aryl chlorides gave the desired products in moderate to excellent yields within hours.
The trinuclear N-heterocyclic carbene-palladium(Ⅱ) complexes were found to be the effective catalyst precursors for the Buchwald-Hartwig amination of aryl chlorides. With catalyst loading of 2.0 mol%, the amination of secondary and primary amines with a variety of electronically and structurally diverse aryl chlorides gave the desired products in moderate to excellent yields within hours.
2018, 38(1): 266-271
doi: 10.6023/cjoc201708053
Abstract:
The peptide transporter family in human body is critical for the transport of peptides and drugs, and the conservative sequences in the peptide transporters play an important role in maintaining its structure and function. In order to understand the function of consensus peptides in peptide transporter and promote the application of oligopeptides in pharmaceutical and medical fields, the signature motif Ⅲ (FYLSINAGS) and its four mutants were synthesized by Fmoc solid phase synthesis method. The products were identified using mass spectrometry, and purified by RP-HPLC. The interaction between peptide and DNA was detected by UV and fluorescence spectrometry. The experimental and structural simulation results showed that the dominant role of electrostatic interaction and intercalation between oligopeptide FYLSINAGG and DNA was related to the concentration of oligopeptide FYLSINAGG, the interaction of FYGLINAGG containing helix structure and DNA was enhanced for the generation of complex, and the interaction between FYGLINKGG hasing helix structure or FYGLINSGG and DNA was attenuated. These results indicated that the serine residue in C-terminal of FYGSINAGS, and the number and position of serine in peptides had great influence on the structure of oligopeptide and its interaction with DNA. The mutation of serine into hydrophobic amino acids is beneficial to form helical structure of oligopeptides and enhance the embedded intercalation with DNA. Thus, serine residues in signature motif are important functional residues, especially at the C-terminus.
The peptide transporter family in human body is critical for the transport of peptides and drugs, and the conservative sequences in the peptide transporters play an important role in maintaining its structure and function. In order to understand the function of consensus peptides in peptide transporter and promote the application of oligopeptides in pharmaceutical and medical fields, the signature motif Ⅲ (FYLSINAGS) and its four mutants were synthesized by Fmoc solid phase synthesis method. The products were identified using mass spectrometry, and purified by RP-HPLC. The interaction between peptide and DNA was detected by UV and fluorescence spectrometry. The experimental and structural simulation results showed that the dominant role of electrostatic interaction and intercalation between oligopeptide FYLSINAGG and DNA was related to the concentration of oligopeptide FYLSINAGG, the interaction of FYGLINAGG containing helix structure and DNA was enhanced for the generation of complex, and the interaction between FYGLINKGG hasing helix structure or FYGLINSGG and DNA was attenuated. These results indicated that the serine residue in C-terminal of FYGSINAGS, and the number and position of serine in peptides had great influence on the structure of oligopeptide and its interaction with DNA. The mutation of serine into hydrophobic amino acids is beneficial to form helical structure of oligopeptides and enhance the embedded intercalation with DNA. Thus, serine residues in signature motif are important functional residues, especially at the C-terminus.
2018, 38(1): 272-276
doi: 10.6023/cjoc201708059
Abstract:
A gold(Ⅰ)-catalyzed 1, 2-silyl migration on 1, 8-di-substituted naphthalene rings was realized by synergistic effect of Lewis acid and water. High yields were achieved under relatively mild conditions.
A gold(Ⅰ)-catalyzed 1, 2-silyl migration on 1, 8-di-substituted naphthalene rings was realized by synergistic effect of Lewis acid and water. High yields were achieved under relatively mild conditions.
2018, 38(1): 277-280
doi: 10.6023/cjoc201707023
Abstract:
An 2-iminophospholide 1 can be obtained via two [1 , 5 ] shifts by reaction of potassium tert-butoxide with 3, 4-di-methyl-1-phenylphosphole and an imidoyl chloride. The reaction of 1 with [Cp*FeCl]n affords a 2-iminophosphaferrocene 2 which behaves as a P, N chelating ligand toward Mo(CO)4 and Rh(CO)2]+. The X-ray crystal structures of 2 and its Mo complex have been recorded.
An 2-iminophospholide 1 can be obtained via two [
