Palladium-catalyzed relay C–H functionalization to construct novel hybrid-arylcyclophosphorus ligand precursors

Citation: Juan Wang, Peng-Bo Bai, Shang-Dong Yang. Palladium-catalyzed relay C–H functionalization to construct novel hybrid-arylcyclophosphorus ligand precursors[J]. Chinese Chemical Letters, 2022, 33(5): 2397-2401. doi: 10.1016/j.cclet.2021.10.019 shu

Palladium-catalyzed relay C–H functionalization to construct novel hybrid-arylcyclophosphorus ligand precursors

English

Palladium-catalyzed relay C–H functionalization to construct novel hybrid-arylcyclophosphorus ligand precursors

a.
State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China
b.
State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
* Corresponding author.
E-mail address: yangshd@lzu.edu.cn (S.-D. Yang).
¹ These two authors contributed equally to this work.
Received Date: 16 July 2021
Accepted Date: 11 October 2021
Revised Date: 06 October 2021
Available Online: 15 May 2022

Abstract: A new relay C–H functionalization of di([1, 1′-biphenyl]-2-yl)phosphine oxide to obtain esterified and hydroxylated products with different hypervalent iodines as oxidants under palladium catalysis is disclosed. This reaction provides a more effective and concise strategy for the synthesis of novel structural hybrid-arylcyclophosphorus ligand precursors with a wide range of substrates and good functional group tolerance.

Key words:

Biaryl phosphorus oxides are a class of important precursors of phosphine-based ligands [1-9]. They are often modified to obtain various hybrid phosphorus compounds via different strategies [10-14]. Recently, cyclic aryl phosphorus oxides have also received much attention for their special properties in fluorescence materials [15-21]. Therefore, searching for a concise and efficient strategy to synthesize various new structural biaryl phosphorus oxides and derivatives is required, which is currently considered a hot topic [22-36]. It is evident from recent literature that C–H activation has emerged as an active field of research [37-50]. In this regard, various aromatic C–H functionalizations involved in diphenylphosphorus oxides have become a most fashionable synthetic strategy [51-56]. In 2011, Taki and coworkers reported an intramolecular dehydrogenative cross-coupling of diphenylphosphine oxides through the palladium-catalyzed C–H activation [57]. In addition, transition-metal catalyzed (2-bromophenyl)diphenylphosphine oxide C–H cyclization also offers a practical pathway [58-61]. Meanwhile, the radical-initiated intermolecular [3 + 2] cycloaddition of diphenylphosphine oxides with alkynes, by C–H activation, to structure biaryl phosphorus oxides has been reported by various research groups [62-72].

Over the past several years, significant progress has been made by various research groups looking into R₂(O)P-directed C(sp²)-H functionalization [73-84]. Subsequently, we selected [1, 1′-biphenyl]-2-yldiphenylphosphine oxides as substrates to realize various C–H functionalizations [85-89], including esterification and hydroxylation (Scheme 1a) [90-90]. We successfully achieved a new relay C–H functionalization of di([1, 1′-biphenyl]-2-yl)phosphine oxide to obtain esterified and hydroxylated products with different hypervalent iodines as oxidant under palladium catalysis (Scheme 1b). This reaction provides a more effective and concise method for the construction of novel hybrid-arylcyclophosphorus ligand precursors.

Scheme 1

Scheme 1. P=O directed C–H esterification and hydroxylation.

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Initially, we selected di([1, 1′-biphenyl]-2-yl)phosphine oxide (1a) as a model substrate under the catalysis of Pd(OAc)₂ (10 mol%), and with PhI(OAc)₂ as both the source of acetate and oxidant, in trifluoroethanol solvent, to carry out the reaction at 100 ℃ (Table 1). To our delight, we obtained the desired product with a yield of 51% when 2.0 equiv. PhI(OAc)₂ was used (entry 1). Encouraged by this result, we proceeded to further optimize the reaction conditions. First, we screened different solvents and found that trifluoroethanol remained the best choice (entries 2–5). TLC monitoring showed formation of the intermediate 5-([1, 1′-biphenyl]-2-yl)benzo[b]phosphindole 5-oxide (m, Scheme 1). Thereafter, it was determined that for this transformation a higher temperature was favorable; the yield of product could be increased to 62% at 120 ℃ (entries 6 and 7). Following on from this, different oxidants, and their content, were carefully screened. The amount of PhI(OAc)₂ is crucial to the successful C–H esterification. When 4.0 equiv. PhI(OAc)₂ was added to the reaction system, the yield of product improved to 92% (entries 8 and 9). Further increasing the PhI(OAc)₂ to 5.0 equiv. did not afford any higher yield (entry 10). Several other oxidants were also investigated (entries 11 and 12). When using oxane in the reaction, only 35% of the product was obtained. Finally, different palladium catalysts, and their content, were further screened. It emerged that Pd(OAc)₂ was most favorable here (entries 13–20).

Table 1

Table 1. Optimization of reaction conditions.^a

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We then investigated the range of substrates, under the optimal reaction conditions, for different substituents (Scheme 2). First, we considered the aromatic ring on the biphenyl group that is not connected to P–H (2b–2e). When one or more electron-donating methyl groups are located at different positions of the aromatic ring, the reaction can proceed smoothly, and medium to high yields can be obtained. It is evident that steric hindrance does not have much effect on it. When a substrate with a strong electron donor (–OMe) is added to the reaction, we achieve a higher conversion rate and obtain a yield of 80% (2f). However, when the substituent is a phenyl group, the yield decreases (2g). Disappointingly, when the electron-withdrawing group is in the para position, the yield is significantly reduced (2h, 2i). It is evident that the electronic effect has a great influence; the electron-withdrawing group is not conducive to the conversion in this reaction. When the substituent is changed to an aromatic ring connected to P–H, the result of the electronic effect is also obvious. It further proves that the conversion effect of the electron-donating group is obviously beneficial to the electron-withdrawing group (2j, 2k). Simultaneously, when all the aromatic rings have electron-donating substituents, the yield is also good (2l, 2m). We successfully recrystallized product 2a as colorless crystals and were able to confirm the molecular structure by X-ray diffraction analysis.

Scheme 2

Scheme 2. Substrate scope of the acetoxylation. Reaction conditions: 1 (0.1 mmol), PhI(OAc)₂ (4.0 equiv.), Pd(OAc)₂ (10 mol%), CF₃CH₂OH (1.0 mL), air atmosphere, 100 ℃. Isolated yields of products.

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Inspired by the success of the above esterification and results recorded in our previous work [12], we proceeded to further realize the hydroxylation using the same strategy. Thus, we investigated the use of different hypervalent iodines, solvents, and reaction temperatures, with Pd(OAc)₂ as catalyst. As expected, the hydroxylated product was successfully obtained in 51% yield when using [bis(trifluoroacetoxy)-iodobenzene] (PhI(OTFA)₂) as oxidant in 1, 2-dichloroethane (DCE) at 60 ℃. We then conducted a specific screening of the reaction conditions and obtained the optimal conditions (for details see Supporting information). Subsequently, we conducted research on different substrates and examined the scope and limitations of this method (Scheme 3). First, the substituents on the aromatic ring not connected to P–H and the steric hindrance effect were investigated. When it contains one or two electron-donating groups, the substrate has better tolerance and a higher yield can be obtained (4a–4c). Unfortunately, when the aromatic ring has a strong electron-withdrawing group, the target product cannot be obtained (4d). When the position of the substituent is changed to the aromatic ring connected with P–H, both the electron-donating and electron-withdrawing substituents can react; however, the yields of the electron-withdrawing products are obviously not as good as those of electron-donating products. It is evident that the electronic effect has a greater impact on the range of the substrate (4e–4g).

Scheme 3

Scheme 3. Substrate scope of the hydroxylation. Reaction conditions: 3 (0.1 mmol), PhI(OTFA)₂ (3.0 equiv.), Pd(OAc)₂ (5 mol%), DCE (1.0 mL), air atmosphere, 100 ℃. Isolated yields of products.

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During the course of the substrate investigations, we found that the electron-deficient groups such as F, CF₃ and ⁿBuCO lay in any aromatic ring, only the cyclization occurred and the corresponding product of 6a-6d was obtained in good yields (Scheme 4). These results indicated that the electronic effect has a greater impact on the C-H esterification or hydroxylation.

Scheme 4

Scheme 4. Scope of the electron-deficient substrate. Reaction conditions: 1 (0.1 mmol), PhI(OAc)₂ (4.0 equiv.), Pd(OAc)₂ (10 mol%), CF₃CH₂OH (1.0 mL), air atmosphere, 120 ℃. Isolated yields of products.

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In the cross-coupling reaction involving transition metals, monophosphorus ligands are important participants. Therefore, we adopted a classic reduction system for its standard products. Fortunately, the reduced product was obtained in a higher yield. Simultaneously, it had been done a grading reaction, the results of which were also very impressive (Scheme 5).

Scheme 5

Scheme 5. Reduction of phosphorous oxides to monophosphorus ligands and gram-scale experiment.

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To demonstrate the utility of our ligands, we used the reduced product of 5a as a ligand to promote the Pd-catalyzed different cross-coupling reactions (Scheme 6). It exhibited the excellent activity in the Suzuki-Miyaura, Heck and Sonogashira coupling reactions and the corresponding coupling product was afforded in the best yield.

Scheme 6

Scheme 6. Synthetic application. Reaction conditions: 7 (0.5 mmol), 8 (0.65 mmol), PdCl₂(PPh3)₂ (0.1 mol%), ligand 5a (1 mol%), and base in solvent (2 mL) at 100 ℃ under argon, 10 h.

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To then further address the reaction mechanism, we conducted control experiments (Scheme 7). First, when Pd(OAc)₂ is not added under standard conditions, 92% of the intermediate cyclic phosphorus product m can be obtained. Based on the above conditions, when radical scavengers (TEMPO) are added, the reaction will not occur. Under standard conditions, the intermediate product m can be obtained without adding an oxidant or adding TEMPO at the same time. It is then evident that the activation of the C–H bond in the first step is a coordinated process of Pd(OAc)₂ and the oxidant.

Scheme 7

Scheme 7. Mechanistic aspect: Control experiments.

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According to results of the above experiments and previous literature reports [57], the possible pathway of this relay C–H functionalization is proposed, as shown in Scheme 8. Initially, the first step of C–H bond cyclization involves two paths, namely the Pudovik reaction process of radicals and the catalytic cycle between Pd(Ⅱ) and Pd(Ⅳ) species. The hypervalent iodine oxidant generates radicals under heating conditions, initiating the activation of the C–H bond of the P radicals, and thereby generating the dibenzophosphorus oxide intermediate m (Path A). Meanwhile, the substrate 1a undergoes oxidative addition, C–H bond activation, and reductive elimination under palladium catalysis to afford the dibenzophosphorus oxide intermediate m (Path B). Subsequently, it is guided by P=O through the 7-membered ring palladium intermediate to then perform the second step in the C–H bond activation, finally affording the desired esterified and hydroxylated products.

Scheme 8

Scheme 8. Proposed reaction mechanism.

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In conclusion, we have developed a novel method for the esterification and hydroxylation of dibenzophosphorus oxide by relay C–H functionalization. The procedure shows good functional group tolerance, and the corresponding products are obtained in high yield and with high selectivity. We envisage that this reaction will offer an effective method for the synthesis of different functionalized diphenyl phosphorus oxides.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

We are grateful to the National Natural Science of China (No. 21532001) and the International Joint Research centre for Green Catalysis and Synthesis (No. 2016B01017) and Lanzhou University for their financial support.

Supplementary materials

Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2021.10.019.
1. [1]
  Y. Uozumi, N. Suzuki, A. Ogiwara, T. Hayashi, Tetrahedron50 (1994) 4293–4302. doi: 10.1016/S0040-4020(01)89366-2
2. [2]
  T. Hayashi, Catal. Today62 (2000) 3–15. doi: 10.1016/S0920-5861(00)00404-1
3. [3]
  T. Hayashi, Acc. Chem. Res. 33 (2000) 354–362. doi: 10.1021/ar990080f
4. [4]
  T. Morimoto, N. Mochizuki, M. Suzuki, Tetrahedron Lett. 45 (2004) 5717–5722. doi: 10.1016/j.tetlet.2004.05.101
5. [5]
  M. Berthod, G. Mignani, G. Woodward, M. Lemaire, Chem. Rev. 105 (2005) 1801–1836. doi: 10.1021/cr040652w
6. [6]
  S. Wang, J. Li, Miao, L. Qiu, et al., Org. Lett. 14 (2012) 1966–1969. doi: 10.1021/ol300721p
7. [7]
  Y. Zhou, X. Zhang, L. Qiu, et al., ACS Catal. 4 (2014) 1390–1397. doi: 10.1021/cs500208n
8. [8]
  Y.N. Ma, S.D. Yang, Chem. Eur. J. 21 (2015) 6673–6677. doi: 10.1002/chem.201406554
9. [9]
  Q.J. Wang, H.H. Wu, J.L. Zhang. ACS Catal. 10 (2020) 1548–1554. doi: 10.3390/polym12071548
10. [10]
  H. Tsuji, K. Sato, Y. Sato, E. Nakamura, Chem. Asian J. 5 (2010) 1294–1297.
11. [11]
  Y. Matano, A. Saito, T. Fukushima, et al., Angew. Chem. Int. Ed. 50 (2011) 8016–8020. doi: 10.1002/anie.201102782
12. [12]
  M. Stolar, T. Baumgartner, Chem. Asian J. 9 (2014) 1212–1225. doi: 10.1002/asia.201301670
13. [13]
  F. Bu, E. Wang, B.Z. Tang, et al., Chem. Eur. J. 21 (2015) 4440–4449. doi: 10.1002/chem.201405902
14. [14]
  E. Yamaguchi, C. Wang, A. Fukazawa, M. Taki, et al., Angew. Chem. Int. Ed. 54 (2015) 4539–4543. doi: 10.1002/anie.201500229
15. [15]
  C. Fave, T.Y. Cho, M. Hissler, et al., J. Am. Chem. Soc. 125 (2003) 9254–9255. doi: 10.1021/ja035155w
16. [16]
  Y. Makioka, T. Hayashi, M. Tanaka, Chem. Lett. 33 (2004) 44–45. doi: 10.1246/cl.2004.44
17. [17]
  F. Mathey, Acc. Chem. Res. 37 (2004) 954–960. doi: 10.1021/ar030118v
18. [18]
  H.C. Su, O. Fadhel, C.J. Yang, T.Y. Cho, et al., J. Am. Chem. Soc. 128 (2006) 983–995. doi: 10.1021/ja0567182
19. [19]
  T. Baumgartner, R. Reau, Chem. Rev. 106 (2006) 4681–4727. doi: 10.1021/cr040179m
20. [20]
  H. Tsuji, K. Sato, Y. Sato, E. Nakamura, J. Mater. Chem. 19 (2009) 3364–3366. doi: 10.1039/b906197e
21. [21]
  Y. Matano, A. Saito, Y. Suzuki et al., Chem. Asian J. 7 (2012) 2305–2312. doi: 10.1002/asia.201200492
22. [22]
  H. Tsuji, S. Komatsu, Y. Kanda, T. Umehara, et al., Chem. Lett. 35 (2006) 758–759. doi: 10.1246/cl.2006.758
23. [23]
  Y. Dienes, M. Eggenstein, T. Karpati, et al., Chem. Eur. J. 14 (2008) 9878–9889. doi: 10.1002/chem.200801549
24. [24]
  A. Fukazawa, M. Hara, T. Okamoto, et al., Org. Lett. 10 (2008) 913–916. doi: 10.1021/ol7030608
25. [25]
  T. Sanji, K. Shiraishi, T. Kashiwabara, M. Tanaka, Org. Lett. 10 (2008) 2689–2692. doi: 10.1021/ol800841v
26. [26]
  Y. Matano, A. Saito, T. Fukushima, et al. Angew. Chem. Int. Ed. 50 (2011) 8016–8020. doi: 10.1002/anie.201102782
27. [27]
  Y. Ren, T. Baumgartner, J. Am. Chem. Soc. 133 (2011) 1328–1340. doi: 10.1021/ja108081b
28. [28]
  A. Bruch, A. Fukazawa, E. Yamaguchi, et al., Angew. Chem. Int. Ed. 50 (2011) 12094–12098. doi: 10.1002/anie.201104114
29. [29]
  Y. Hayashi, Y. Matano, K. Suda, et al., Chem. Eur. J. 18 (2012) 15972–15983. doi: 10.1002/chem.201203047
30. [30]
  Y. Sawada, S. Furumi, A. Takai, et al., J. Am. Chem. Soc. 134 (2012) 4080–4083. doi: 10.1021/ja300278e
31. [31]
  B. Wu, M. Santra, N. Yoshikai, Angew. Chem. Int. Ed. 53 (2014) 7543–7546. doi: 10.1002/anie.201404019
32. [32]
  B. Li, M.K. Zhang, X.L. Huang, Z.H. Gu, Org. Chem. Front. 4 (2017) 1854–1857. doi: 10.1039/C7QO00310B
33. [33]
  E. Si, P. Zhao, L.L. Wang, Z. Duan, F. Mathey, Eur. J. Org. Chem. 2020 (2020) 697–701. doi: 10.1002/ejoc.201901753
34. [34]
  H. Fujimoto, M. Kusano, T. Kodama, M. Tobisu, Org. Lett. 22 (2020) 2293–2297. doi: 10.1021/acs.orglett.0c00489
35. [35]
  K. Nishimura, K. Hirano, M. Miura, Org. Lett. 22 (2020) 3185–3189. doi: 10.1021/acs.orglett.0c00944
36. [36]
  Y. Kurimoto, J. Yamashita, K. Mitsudo, E. Sato, S. Suga, Org. Lett. 23 (2021) 3120–3124. doi: 10.1021/acs.orglett.1c00807
37. [37]
  D. Alberico, M.E. Scott, M. Lautens, Chem. Rev. 107 (2007) 174–238. doi: 10.1021/cr0509760
38. [38]
  T.W. Lyons, M.S. Sanford, Chem. Rev. 110 (2010) 1147–1169. doi: 10.1021/cr900184e
39. [39]
  C.L. Sun, B.J. Li, Z.J. Shi, Chem. Rev. 111 (2011) 1293–1314. doi: 10.1021/cr100198w
40. [40]
  K.M. Engle, T.S. Mei, M. Wasa, J.Q. Yu, Acc. Chem. Res. 45 (2011) 788–802.
41. [41]
  N. Kuhl, M.N. Hopkinson, J.W. Delord, F. Glorius, Angew. Chem. Int. Ed. 51 (2012) 10236–10254. doi: 10.1002/anie.201203269
42. [42]
  J.K. Wang, Y.X. Zong, G.R. Yue, et al., Chin. Chem. Lett. 26 (2015) 1376–1380. doi: 10.1016/j.cclet.2015.08.001
43. [43]
  C. Wang, L. Luo, H. Yamamoto, Acc. Chem. Res. 49 (2016) 193–204. doi: 10.1021/acs.accounts.5b00428
44. [44]
  J.A. Labinger, Chem. Rev. 117 (2017) 8483–8496. doi: 10.1021/acs.chemrev.6b00583
45. [45]
  M. Parasram, V. Gevorgyan, Acc. Chem. Res. 50 (2017) 2038–2053. doi: 10.1021/acs.accounts.7b00306
46. [46]
  C. Sambiagio, D. Schönbauer, M. Schnürch, et al., Chem. Soc. Rev. 47 (2018) 6603–6743.
47. [47]
  Q. Shao, K. Wu, Z. Zhuang, S. Qian, J.Q. Yu, Acc. Chem. Res. 53 (2020) 833–851. doi: 10.1021/acs.accounts.9b00621
48. [48]
  K.J. Jiao, Y.K. Xing, Q.L. Yang, H. Qiu, T.S. Mei, Acc. Chem. Res. 53 (2020) 300–310. doi: 10.1021/acs.accounts.9b00603
49. [49]
  K. Yang, Y. Li, M. Song, et al., Chin. Chem. Lett. 32 (2021) 146–149. doi: 10.1016/j.cclet.2020.11.036
50. [50]
  L. Liu, H. Liu, Z. Zuo et al., Chin. Chem. Lett. 32 (2021) 239–242.
51. [51]
  K. Baba, M. Tobisu, N. Chatani, Angew. Chem. Int. Ed. 52 (2013) 11892–11895. doi: 10.1002/anie.201307115
52. [52]
  S. Hashimoto, S. Nakatsuka, M. Nakamura, T. Hatakeyama, Angew. Chem. Int. Ed. 53 (2014) 14074–14076. doi: 10.1002/anie.201408390
53. [53]
  S. Furukawa, S. Haga, J. Kobayashi, T. Kawashima, Org. Lett. 16 (2014) 3228–3231. doi: 10.1021/ol501189u
54. [54]
  Z. Lian, B.N. Bhawal, P. Yu, B. Morandi, Science. 356 (2017) 1059–1063. doi: 10.1126/science.aam9041
55. [55]
  K. Nishimura, K. Hirano, M. Miura, Org. Lett. 21 (2019) 1467–1470. doi: 10.1021/acs.orglett.9b00219
56. [56]
  H. Fujimoto, M. Kusano, T. Kodama, M. Tobisu, Org. Lett. 21 (2019) 4177–4181. doi: 10.1021/acs.orglett.9b01355
57. [57]
  Y. Kuninobu, T. Yoshida, K. Takai, J. Org. Chem. 76 (2011) 7370–7376. doi: 10.1021/jo201030j
58. [58]
  Y.M. Cui, L.Z. Fu, J. Cao, et al., Adv. Synth. Catal. 356 (2014) 1217–1222. doi: 10.1002/adsc.201301081
59. [59]
  K. Baba, M. Tobisu, N. Chatani, Org. Lett. 17 (2015) 70–73. doi: 10.1021/ol503252t
60. [60]
  Y. Lin, W.Y. Ma, Q.Y. Sun, Y.M. Cui, L.W. Xu, Synlett28 (2017) 1432–1436. doi: 10.1055/s-0036-1588983
61. [61]
  Z. Li, Z.Q. Lin, C.G. Yan, W.L. Duan, Organometallics38 (2019) 3916–3920. doi: 10.1021/acs.organomet.9b00216
62. [62]
  Y.R. Chen, W.L. Duan, J. Am. Chem. Soc. 135 (2013) 16754–16757. doi: 10.1021/ja407373g
63. [63]
  Y. Unoh, K. Hirano, T. Satoh, M. Miura, Angew. Chem. Int. Ed. 52 (2013) 12975–12979. doi: 10.1002/anie.201307211
64. [64]
  P. Zhang, Y. Gao, L. Zhang, et al., Adv. Synth. Catal. 358 (2016) 138–142. doi: 10.1002/adsc.201500667
65. [65]
  D.M. Ma, W.Z. Chen, Y.F. Zhao, et al., Green Chem. 18 (2016) 3522–3526. doi: 10.1039/C6GC01009A
66. [66]
  V. Quint, F. MorletSavary, J.F. Lohier, et al., J. Am. Chem. Soc. 138 (2016) 7436–7441. doi: 10.1021/jacs.6b04069
67. [67]
  J. Li, W.W. Zhang, X.J. Wei, B. Jiang, et al., Org. Lett. 19 (2017) 4512–4515. doi: 10.1021/acs.orglett.7b02071
68. [68]
  D. M Ma, J.T. Pan, Y.F. Zhao, et al., Org. Lett. 20 (2018) 3455–3459. doi: 10.1021/acs.orglett.8b01108
69. [69]
  K. Nishimura, Y. Unoh, K. Hirano, M. Miura, Chem. Eur. J. 24 (2018) 13089–13092. doi: 10.1002/chem.201803225
70. [70]
  L.X. Liu, J.Y. Dong, Y.B. Zhou, et al., Chem. Commun. 55 (2019) 233–236. doi: 10.1039/c8cc08689c
71. [71]
  H. Hou, Y. Xu, H.B. Yang, S.Q. Zhu, et al., Org. Biomol. Chem. 17 (2019) 8175–8184. doi: 10.1039/c9ob01585j
72. [72]
  W.Q. Liu, T. Lei, S. Zhou, L.Z. Wu, et al., J. Am. Chem. Soc. 141 (2019) 13941–13947. doi: 10.1021/jacs.9b06920
73. [73]
  D. Zhao, C. Nimphius, M. Lindale, F. Glorius, Org. Lett. 15 (2013) 4504–4507. doi: 10.1021/ol402053n
74. [74]
  D. Eom, Y. Jeong, P.H. Lee, et al., Org. Lett. 15 (2013) 5210–5213. doi: 10.1021/ol402736v
75. [75]
  L.Y. Chan, L. Cheong, S. Kim, Org. Lett. 15 (2013) 2186–2189. doi: 10.1021/ol400732q
76. [76]
  L. Liu, H. Yuan, T. Fu, Y.J. Zhao, et al., J. Org. Chem. 79 (2014) 80–87.
77. [77]
  D. Gwon, D. Lee, J. Kim, S. Park, S. Chang, Chem. Eur. J. 20 (2014) 12421–12425. doi: 10.1002/chem.201404151
78. [78]
  K.M. Crawford, T.R. Ramseyer, C.J.A. Daley, T.B. Clark, Angew. Chem. Int. Ed. 53 (2014) 7589–7593. doi: 10.1002/anie.201402868
79. [79]
  X.H. Hu, X.F. Yang, T.P. Loh, Angew. Chem. Int. Ed. 54 (2015) 15535–15539. doi: 10.1002/anie.201506437
80. [80]
  Y. Unoh, T. Satoh, K. Hirano, M. Miura, ACS Catal. 5 (2015) 6634–6639. doi: 10.1021/acscatal.5b01896
81. [81]
  Z.J. Du, J. Guan, F.S. Han, J. Am. Chem. Soc. 137 (2015) 632–635. doi: 10.1021/ja512029x
82. [82]
  T.T. Nguyen, L. Grigorjeva, O. Daugulis, ACS Catal. 6 (2016) 551–554. doi: 10.1021/acscatal.5b02391
83. [83]
  Y. Yang, X. Qiu, Z. Shi, J. Am. Chem. Soc. 138 (2016) 495–498. doi: 10.1021/jacs.5b11569
84. [84]
  Y.S. Jang, M. Dieckmann, N. Cramer, Angew. Chem. Int. Ed. 56 (2017) 15088–15092. doi: 10.1002/anie.201708440
85. [85]
  S.X. Li, Y.N. Ma, S.D. Yang, Org. Lett. 19 (2017) 1842–1845. doi: 10.1021/acs.orglett.7b00608
86. [86]
  Y.N. Ma, S.X. Li, S.D. Yang, Acc. Chem. Res. 50 (2017) 1480–1492. doi: 10.1021/acs.accounts.7b00167
87. [87]
  C. Li, X.Y. Qiang, Z.C. Qi, S.D. Yang, Org. Lett. 21 (2019) 7138–7142. doi: 10.1021/acs.orglett.9b02697
88. [88]
  Y. Niu, Z.C. Qi, Q.X. Lou, P.B. Bai, S.D. Yang, Chem. Commun. 56 (2020) 14721–14724. doi: 10.1039/d0cc06639g
89. [89]
  Z.C. Qi, Q.X. Lou, Y. Niu, S.D. Yang, Chem. Commun. 57 (2021) 2021–2024. doi: 10.1039/d0cc07596e
90. [90]
  H.Y. Zhang, H.M. Yi, G.W. Wang, B. Yang, S.D. Yang, Org. Lett. 15 (2013) 6186–6189. doi: 10.1021/ol403028a
91. [91]
  H. Zhang, R.B. Hu, X.Y. Zhang, S.X. Li, S.D. Yang, Chem. Commun. 50 (2014) 4686–4689. doi: 10.1039/C4CC01238K
Scheme 1 P=O directed C–H esterification and hydroxylation.

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Scheme 2 Substrate scope of the acetoxylation. Reaction conditions: 1 (0.1 mmol), PhI(OAc)₂ (4.0 equiv.), Pd(OAc)₂ (10 mol%), CF₃CH₂OH (1.0 mL), air atmosphere, 100 ℃. Isolated yields of products.

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Scheme 3 Substrate scope of the hydroxylation. Reaction conditions: 3 (0.1 mmol), PhI(OTFA)₂ (3.0 equiv.), Pd(OAc)₂ (5 mol%), DCE (1.0 mL), air atmosphere, 100 ℃. Isolated yields of products.

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Scheme 4 Scope of the electron-deficient substrate. Reaction conditions: 1 (0.1 mmol), PhI(OAc)₂ (4.0 equiv.), Pd(OAc)₂ (10 mol%), CF₃CH₂OH (1.0 mL), air atmosphere, 120 ℃. Isolated yields of products.

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Scheme 5 Reduction of phosphorous oxides to monophosphorus ligands and gram-scale experiment.

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Scheme 6 Synthetic application. Reaction conditions: 7 (0.5 mmol), 8 (0.65 mmol), PdCl₂(PPh3)₂ (0.1 mol%), ligand 5a (1 mol%), and base in solvent (2 mL) at 100 ℃ under argon, 10 h.

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Scheme 7 Mechanistic aspect: Control experiments.

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Scheme 8 Proposed reaction mechanism.

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Table 1. Optimization of reaction conditions.^a

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