Login In
2015 Volume 36 Issue 1
2015, 36(1):
Abstract:
2015, 36(1): 1-1
doi: 10.1016/S1872-2067(14)60260-6
Abstract:
2015, 36(1): 2-2
doi: 10.1016/S1872-2067(14)60266-7
Abstract:
2015, 36(1): 3-14
doi: 10.1016/S1872-2067(14)60217-5
Abstract:
A variety of Ni catalyzed cross-coupling reactions have emerged as efficient new methods for the construction of C-C bonds, and many mechanistic studies have been conducted to understand the factors controlling the reactivity and selectivity of Ni catalyzed reactions. The mechanisms of Ni catalyzed reactions are often very different from the corresponding Pd catalyzed processes because radical or bimetallic pathways are frequently involved in Ni catalyzed cross-coupling reactions. This review summarized recent advances in the mechanism of Ni catalyzed cross-coupling reactions. These are important for the development of new Ni catalyzed cross-coupling reactions with improved efficiency and selectivity.
A variety of Ni catalyzed cross-coupling reactions have emerged as efficient new methods for the construction of C-C bonds, and many mechanistic studies have been conducted to understand the factors controlling the reactivity and selectivity of Ni catalyzed reactions. The mechanisms of Ni catalyzed reactions are often very different from the corresponding Pd catalyzed processes because radical or bimetallic pathways are frequently involved in Ni catalyzed cross-coupling reactions. This review summarized recent advances in the mechanism of Ni catalyzed cross-coupling reactions. These are important for the development of new Ni catalyzed cross-coupling reactions with improved efficiency and selectivity.
2015, 36(1): 15-18
doi: 10.1016/S1872-2067(14)60191-1
Abstract:
An efficient method has been developed for the Pd(0)-catalyzed benzylation of indoles, which occurred with exclusive regioselectivity. When this reaction was performed in the presence of Pd(PPh3)4, it provided access to a broad range of substituted indoles bearing diarylmethanes at their 3-position in 90%-99% yields under mild conditions.
An efficient method has been developed for the Pd(0)-catalyzed benzylation of indoles, which occurred with exclusive regioselectivity. When this reaction was performed in the presence of Pd(PPh3)4, it provided access to a broad range of substituted indoles bearing diarylmethanes at their 3-position in 90%-99% yields under mild conditions.
2015, 36(1): 19-23
doi: 10.1016/S1872-2067(14)60196-0
Abstract:
The direct synthesis of imines from amines or alcohols and amines by vanadium catalyzed aerobic oxidation was developed. Without an additive or promoter, various symmetrical and unsymmetrical imines were obtained in good to excellent yields under mild conditions with air as an environmentally benign oxidant. The catalyst is very easy to prepare and use, and this catalytic system is also effective for the synthesis of heteroatom-containing imines.
The direct synthesis of imines from amines or alcohols and amines by vanadium catalyzed aerobic oxidation was developed. Without an additive or promoter, various symmetrical and unsymmetrical imines were obtained in good to excellent yields under mild conditions with air as an environmentally benign oxidant. The catalyst is very easy to prepare and use, and this catalytic system is also effective for the synthesis of heteroatom-containing imines.
2015, 36(1): 24-32
doi: 10.1016/S1872-2067(14)60201-1
Abstract:
Cyclooctatetraenes, including dibenzocyclooctatetraenes, are structurally interesting compounds and are widely used in many areas. Therefore, the development of synthetic methods for such compounds has long been attractive. In this work, a Pd-catalyzed coupling reaction between alkenylbromides and arylbromides has been realized. Multi-substituted 1,4-dibromo-1,3-butadienes and o-bromo-2-(2-bromovinyl)benzenes underwent a Pd-catalyzed cyclodimerization reaction to afford the corresponding multi-substituted cyclooctatetraenes and dibenzo[a,e] cyclooctatetraenes, respectively, in high yields and with excellent regioselectivity.
Cyclooctatetraenes, including dibenzocyclooctatetraenes, are structurally interesting compounds and are widely used in many areas. Therefore, the development of synthetic methods for such compounds has long been attractive. In this work, a Pd-catalyzed coupling reaction between alkenylbromides and arylbromides has been realized. Multi-substituted 1,4-dibromo-1,3-butadienes and o-bromo-2-(2-bromovinyl)benzenes underwent a Pd-catalyzed cyclodimerization reaction to afford the corresponding multi-substituted cyclooctatetraenes and dibenzo[a,e] cyclooctatetraenes, respectively, in high yields and with excellent regioselectivity.
2015, 36(1): 33-39
doi: 10.1016/S1872-2067(14)60243-6
Abstract:
A highly selective procedure has been developed for the partial dehydrogenation of 1-substituted-1,2,3,4-tetrahydroisoquinolines over K3PO4×3H2O-modified Pd/C catalyst. This new method provides facile, atom-economical and environmentally friendly access to 1-substituted-3,4-dihydroisoquinolines without the need for stoichiometric amounts of harmful oxidants. The use of standard Pd/C as a catalyst for this process gave poor chemoselectivity. Pleasingly, the use of a K3PO4×3H2O-modified Pd/C catalyst promoted the partial dehydrogenation of 1-substituted-1,2,3,4-tetrahydroisoquinolines with excellent chemoselectivity by suppressing further dehydroaromatization. Furthermore, conducting the reaction under an atmosphere of oxygen led to further improvements in the chemoselectivity of the dehydrogenation, with the ratio of imine to isoquinoline reaching up to 32/1. The heterogenous Pd/C catalyst could also be recycled and reused at least three times with excellent conversion and chemoselectivity, demonstrating the significantly practical potential of this methodology.
A highly selective procedure has been developed for the partial dehydrogenation of 1-substituted-1,2,3,4-tetrahydroisoquinolines over K3PO4×3H2O-modified Pd/C catalyst. This new method provides facile, atom-economical and environmentally friendly access to 1-substituted-3,4-dihydroisoquinolines without the need for stoichiometric amounts of harmful oxidants. The use of standard Pd/C as a catalyst for this process gave poor chemoselectivity. Pleasingly, the use of a K3PO4×3H2O-modified Pd/C catalyst promoted the partial dehydrogenation of 1-substituted-1,2,3,4-tetrahydroisoquinolines with excellent chemoselectivity by suppressing further dehydroaromatization. Furthermore, conducting the reaction under an atmosphere of oxygen led to further improvements in the chemoselectivity of the dehydrogenation, with the ratio of imine to isoquinoline reaching up to 32/1. The heterogenous Pd/C catalyst could also be recycled and reused at least three times with excellent conversion and chemoselectivity, demonstrating the significantly practical potential of this methodology.
2015, 36(1): 40-47
doi: 10.1016/S1872-2067(14)60164-9
Abstract:
A facile Pd-catalyzed intramolecular aminofluorination reaction of allylic sulfamides was developed that can be used to prepare fluorinated 1,3-diamine derivatives. Acetic acid was essential for regulation to give the major 6-endo cyclization products.
A facile Pd-catalyzed intramolecular aminofluorination reaction of allylic sulfamides was developed that can be used to prepare fluorinated 1,3-diamine derivatives. Acetic acid was essential for regulation to give the major 6-endo cyclization products.
2015, 36(1): 48-56
doi: 10.1016/S1872-2067(14)60245-X
Abstract:
Rh(III)-catalyzed C-H activation of N-(alkyl)benzamides in the oxidative coupling with various quinones. In addition, under redox-neutral conditions, 2-hydroxy-6H-benzo[c]chromen-6-ones were also obtained via a cascade of cross-coupling followed by lactonization.
Rh(III)-catalyzed C-H activation of N-(alkyl)benzamides in the oxidative coupling with various quinones. In addition, under redox-neutral conditions, 2-hydroxy-6H-benzo[c]chromen-6-ones were also obtained via a cascade of cross-coupling followed by lactonization.
2015, 36(1): 57-67
doi: 10.1016/S1872-2067(14)60199-6
Abstract:
A series of efficient catalytic systems has been developed to control the dual enantioselectivity of the conjugate addition of α-keto esters to nitroalkenes. The use of the chiral diamine (1S,1'S)-1,1'-biisoindoline as a chiral ligand with either (Cu(OAc)2·H2O or Ni(OAc)2·4H2O as the catalyst provide facile access to the respective enantiomers resulting from the conjugate addition reaction with high levels of enantioselectivity (94% ee vs 93% ee). Furthermore, the use of Cu(OAc)2·H2O as the metal center allowed the enantioselectivity of the conjugate addition reaction to be switched through the tuning of the rigidity of the chiral diamine ligand (94% ee vs 94% ee).
A series of efficient catalytic systems has been developed to control the dual enantioselectivity of the conjugate addition of α-keto esters to nitroalkenes. The use of the chiral diamine (1S,1'S)-1,1'-biisoindoline as a chiral ligand with either (Cu(OAc)2·H2O or Ni(OAc)2·4H2O as the catalyst provide facile access to the respective enantiomers resulting from the conjugate addition reaction with high levels of enantioselectivity (94% ee vs 93% ee). Furthermore, the use of Cu(OAc)2·H2O as the metal center allowed the enantioselectivity of the conjugate addition reaction to be switched through the tuning of the rigidity of the chiral diamine ligand (94% ee vs 94% ee).
2015, 36(1): 68-77
doi: 10.1016/S1872-2067(14)60204-7
Abstract:
Bioactive 5-aza-spiro[2,4]heptanes with high functionality and up to three contiguous all-carbon quaternary stereogenic centers were synthesized by Cu(I)-catalyzed asymmetric endo-selective 1,3-dipolar cycloaddition of azomethine ylides with cyclopropylidene acetates. This synthesis system performs well for a broad scope of substrates. α-unsubstituted/α-substituted azomethine ylides and cyclopropylidene acetates are compatible 1,3-dipoles and dipolarophiles, which afford the spiro heterocycles with contiguous quaternary centers at 2-, 3- and 4-positions of the pyrrolidine ring in good yield (up to 97%) and high diastereoselectivity (95:5->98:2 d.r) and excellent enantioselectivity (87%-98% ee).
Bioactive 5-aza-spiro[2,4]heptanes with high functionality and up to three contiguous all-carbon quaternary stereogenic centers were synthesized by Cu(I)-catalyzed asymmetric endo-selective 1,3-dipolar cycloaddition of azomethine ylides with cyclopropylidene acetates. This synthesis system performs well for a broad scope of substrates. α-unsubstituted/α-substituted azomethine ylides and cyclopropylidene acetates are compatible 1,3-dipoles and dipolarophiles, which afford the spiro heterocycles with contiguous quaternary centers at 2-, 3- and 4-positions of the pyrrolidine ring in good yield (up to 97%) and high diastereoselectivity (95:5->98:2 d.r) and excellent enantioselectivity (87%-98% ee).
2015, 36(1): 78-85
doi: 10.1016/S1872-2067(14)60247-3
Abstract:
A new method has been developed for the cross-coupling of aryl halides with β-chloroalkyl aryl ketones and their ester and amide analogs through a domino dehydrochlorination/Pd(OAc)2-catalyzed Heck reaction sequence. The enone intermediates generated in situ reduced the occurrence of side reactions and therefore enhanced the efficiency of the reaction. This reaction exhibited good tolerance to various functional groups on both substrates and provides rapid access to a wide range of chalcone derivatives.
A new method has been developed for the cross-coupling of aryl halides with β-chloroalkyl aryl ketones and their ester and amide analogs through a domino dehydrochlorination/Pd(OAc)2-catalyzed Heck reaction sequence. The enone intermediates generated in situ reduced the occurrence of side reactions and therefore enhanced the efficiency of the reaction. This reaction exhibited good tolerance to various functional groups on both substrates and provides rapid access to a wide range of chalcone derivatives.
2015, 36(1): 86-92
doi: 10.1016/S1872-2067(14)60230-8
Abstract:
The synthesis of optically active N-propargylindoles has been accomplished via the Cu-catalyzed asymmetric propargylic alkylation of indolines with propargylic esters, followed by the dehydrogenation of the resulting N-substituted indolines with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. The reaction proceeded in good yield with high enantioselectivity under mild conditions using a bulky and structurally rigid tridentate ketimine P,N,N-ligand, and exhibited a broad substrate scope.
The synthesis of optically active N-propargylindoles has been accomplished via the Cu-catalyzed asymmetric propargylic alkylation of indolines with propargylic esters, followed by the dehydrogenation of the resulting N-substituted indolines with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. The reaction proceeded in good yield with high enantioselectivity under mild conditions using a bulky and structurally rigid tridentate ketimine P,N,N-ligand, and exhibited a broad substrate scope.
2015, 36(1): 93-99
doi: 10.1016/S1872-2067(14)60225-4
Abstract:
Various substituted dibenzo[b,f][1,4]oxazepines as seven-membered cyclic imines underwent a highly enantioselective direct Mannich reaction with acetone when catalyzed by proline. These reactions gave a range of optically active β-carbonyl seven-membered N-heterocycles with excellent enantioselectivity (93%-98% ee). With 2-butanone as a Mannich donor, the single regioselective product was obtained with 96%-97% ee. The absolute configuration of the product was assigned to be R by X-ray single crystal analysis of its derivative.
Various substituted dibenzo[b,f][1,4]oxazepines as seven-membered cyclic imines underwent a highly enantioselective direct Mannich reaction with acetone when catalyzed by proline. These reactions gave a range of optically active β-carbonyl seven-membered N-heterocycles with excellent enantioselectivity (93%-98% ee). With 2-butanone as a Mannich donor, the single regioselective product was obtained with 96%-97% ee. The absolute configuration of the product was assigned to be R by X-ray single crystal analysis of its derivative.
2015, 36(1): 100-105
doi: 10.1016/S1872-2067(14)60241-2
Abstract:
A spiro bisphosphine oxide (SpinPO) was found to be an efficient chiral Lewis base catalyst in asymmetric reductive aldol reaction of enones and aldehydes in the presence of trichlorosilane as the reductant, affording a variety of β-hydroxyketones in good yields with moderate to high levels of diastereo- and enantioselectivities.
A spiro bisphosphine oxide (SpinPO) was found to be an efficient chiral Lewis base catalyst in asymmetric reductive aldol reaction of enones and aldehydes in the presence of trichlorosilane as the reductant, affording a variety of β-hydroxyketones in good yields with moderate to high levels of diastereo- and enantioselectivities.
2015, 36(1): 106-112
doi: 10.1016/S1872-2067(14)60246-1
Abstract:
A new protocol that enables asymmetric hydroaminomethylation of styrenes to afford chiral amines has been developed. Catalysed by an Rh-phosphine species and a chiral phosphoric acid, styrenes are converted into β-chiral amines with good enantioselectivities under syngas in the presence of an amine and Hantzsch ester. The reaction involves two key steps, hydroformylation and reductive amination, with the former catalysed by the Rh species whilst the latter by the phosphoric acid.
A new protocol that enables asymmetric hydroaminomethylation of styrenes to afford chiral amines has been developed. Catalysed by an Rh-phosphine species and a chiral phosphoric acid, styrenes are converted into β-chiral amines with good enantioselectivities under syngas in the presence of an amine and Hantzsch ester. The reaction involves two key steps, hydroformylation and reductive amination, with the former catalysed by the Rh species whilst the latter by the phosphoric acid.
2015, 36(1): 113-118
doi: 10.1016/S1872-2067(14)60220-5
Abstract:
A green organic synthetic method combining reductive acylation of ketoximes and oxidative coupling of terminal alkynes was developed. This novel process enables enamides and 1,3-diynes to be synthesized simultaneously in high yields and under mild conditions without the use of terminal reductants/oxidants.
A green organic synthetic method combining reductive acylation of ketoximes and oxidative coupling of terminal alkynes was developed. This novel process enables enamides and 1,3-diynes to be synthesized simultaneously in high yields and under mild conditions without the use of terminal reductants/oxidants.
