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Organocatalytic asymmetric Michael addition of 3-substituted oxindoles to α,β-unsaturated acyl phosphonates for the synthesis of 3,3'disubstituted oxindoles with chiral squaramides 5

Lin Chen,a,b Yong You, a,b Ming-Liang Zhang, a,b Jian-qiang Zhao, a,b Jian Zuo, a,b Xiao-Mei Zhang,a WeiCheng Yuan* ,a and Xiao-Ying Xu* ,a Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX DOI: 10.1039/b000000x

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A highly enantioselective Michael addition of 3monosubstituted oxindoles to α,β-unsaturated acyl phosphonates with chiral squaramides as catalysts was investigated for the first time. A wide range of 3,3'disubstituted oxindole adducts bearing adjacent quaternary and tertiary stereogenic centres could be smoothly obtained in good yields (up to 98%), diastereo- (up to >99:1 dr) and enantioselectivities (up to 98% ee) with the developed protocols.

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Introduction

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Optically active 3,3' -disubstituted oxindoles are frequently found in a wide variety of natural products and pharmaceutically relevant compounds.1 Consequently, many elegant synthetic methods for the construction of those privileged structural motifs have been developed.1,2 Among the developed methods, M ichael addition of 3-monosubstituted oxindoles to various electrondeficient olefins is the most straightforward way to access versatile 3,3’-disubstituted oxindoles.3 Survey of the literatures revealed that the M ichael acceptors involved in those protocols generally have been limited to nitroolefins, 3a-g, 4 α,β-unsaturated carbonyl compounds, 3h-j, 5 allenes,6 vinyl sulfones,7 vinyl selenones,8 maleimides,9 2-chloroacrylonitrile,10 2-phthalimidoacrylates11 and quinones 12 etc. However, no report has yet been released relating to the use of α,β-unsaturated acyl phosphonates 13 as M ichael acceptors for the construction of 3-γesters-3,3'-disubstituted oxindoles which are extremely versatile building blocks that could undergo synthetically useful transformations.14  Over the past decade, asymmetric organocatalysis had been proven to be a powerful tool for the construction of optically pure compounds due to its operational and economic advantages. 15 Among the supreme achievements gained in asymmetric

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This journal is © The Royal Society of Chemistry [year]

Scheme 1 Design strategy for the construction of 3,3'- disubstituted oxindoles via asymmetric Michael addition of 3-substituted oxindoles to α,β-unsaturated acyl phosphonates

Results and Discussion

a

National Engineering Research Center of Chiral Drugs, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041,China. E-mail: [email protected], [email protected]; Fax: +86-028-8523-1007 b University of Chinese Academy of Sciences, Beijing 100049, China †Electronic Supplementary Information (ESI) available: See DOI: 10.1039/b000000x/

organocatalysis, bifunctional chiral squaramides with various chiral scaffolds have been successfully applied in a range of asymmetric transformations for their superiority in activity and stereoinduction.16 M eanwhile, our group has recently become interested in the preparation of multifarious oxindole derivatives and we have successfully developed a few protocols. 17 In this context, as part of our ongoing investigations aimed at developing new strategies for the synthesis of diversely structured 3,3'disubstituted oxindole compounds, we envisioned that asymmetric M ichael addition of 3-monosubstituted oxindoles to α,β-unsaturated acyl phosphonates would be achieved in the presence of chiral squaramides via the double active model. Subsequently, the intermediate 3,3'-disubstituted oxindole acyl phosphonates would be converted to the corresponding esters or amides by direct addition of alcohols or amines, resulting in the desired 3,3'-disubstituted oxindole compounds with γ-esters or γamides at C3-position (Scheme 1). Herein, we will report our original study about this transformation.

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To validate our hypothesis, the reaction of 3-benzyl-2oxoindoline 1a with diethyl but-2-enoylphosphonate 2a was selected as a model reaction. Initially, chiral cyclohexanediamine derived squaramide 4a (Fig. 1) was used to catalyze the model [journal], [year], [vol], 00–00 | 1

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reaction in 2 mL DCM at room temperature. Delightfully, it was found that the reaction proceeded smoothly and the desired 3,3’disubstituted oxindole 3aa was obtained in 65% yield and 49% ee after treatment with M eOH (Table 1, entry 1). However, catalyst 4b with a cyclic substitutent on nitrogen atom gave poor enantioslectivity (Table 1, entry 2). Squaramides 4c and 4d with different chiral scaffolds were also tested. We were pleased to observe that quinine based squaramide 4d could afford relative better ee value (Table 1, entry 4 vs. entries 1-3). Consequently, the effects of solvents, the molar ratio of the substrates and reaction temperature for this transformation were further investigated with catalyst 4d. It was revealed that various solvents were well tolerated and ether was identified as the most favorable solvent (Table 1, entry 7 vs. entries 4-6, 8). A survey of molar ratio of the substrates revealed that excessive 2a (2 equiv.) was beneficial to this transformation (Table 1, entry 9). To our delight, the enantioselectivity was further improved to 90% ee when the transformation was conducted at -20 oC (Table 1, entry 12). Further lowering the temperature to -30 oC, the enantioselectivity increased slightly whereas the yield decreased dramatically (Table 1, entry 13). Subsequently, more catalysts were further investigated in ether at -20 oC with 2 equiv. of 2a (Table 1, entries 14-16). It was found that catalyst 4g could give excellent enantioselectivity (98% ee) with poor yield (Table 1, entry 16). Fortunately, increasing the amount of 2a to 3 equiv.

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Table 1 Optimization of reaction conditionsa 55

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Entry

Cat.

1a:2a

Solvent

1 2 3 4 5 6 7 8 9 10 11 e 12 f 13 g 14 f 15 f 16 f 17 f 18 f

4a 4b 4c 4d 4d 4d 4d 4d 4d 4d 4d 4d 4d 4e 4f 4g 4g 4g

1:1 1:1 1:1 1:1 1:1 1:1 1:1 1:1 1:2 2:1 1:2 1:2 1:2 1:2 1:2 1:2 1:3 1:4

DCM DCM DCM DCM Toluene n-Hexane Et 2 O CH3 CN Et 2 O Et 2 O Et 2 O Et 2 O Et 2 O Et 2 O Et 2 O Et 2 O Et 2 O Et 2 O

T ime (h) 22 72 96 22 4 7 1 3 1 1 18 40 96 72 72 72 22 22

b

c

Yield

Dr

65 56 54 42 46 31 40 66 48 25 45 41 28 13 23 24 68 82

7.9:1 5.8:1 12.6:1 12.7:1 9.5:1 9.3:1 12.9:1 14.2:1 12.3:1 12.6:1 20.7:1 27.2:1 33.2:1 30:0:1 52.6:1 54.1:1 9.6:1 8.9:1

Eed (%) 49 29 54 65 65 71 78 60 78 79 88 90 92 89 97 98 85 83

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Therefore, the molar ratio of 1a to 2a was established as 1:4 in terms of yield and ee value (Table 1, entry 18). After those screenings, we have established the optimal reaction conditions for this transformation: 0.1 mmol 1a and 4 equiv. of 2a in 2 mL ether with 20 mol% 4g as the catalyst at -20 oC.

Fig. 1 Chiral squaramide catalysts screened in this transformation

With the optimized conditions in hand, the generality of the M ichael reaction with respect to N-Boc-3-benzyl-2-oxoindoline 1a and various α,β-unsaturated acyl phosphonates 2 was first investigated (Table 2). As shown in Table 2, the reactions tolerated both aliphatic and aromatic substituents R1 on α,βunsaturated acyl phosphonates, affording the desired 3,3’disubstituted oxindoles in 61-82% yield and 74-93% ee. The substituents of esters on acyl phosphonates had slight effects on the enantioselectivites (77-88% ee) and the bulky butyl group gave relative higher ee value (Table 2, entry 4 vs. entries 1-3). With respect to the alkyl substituted α,β-unsaturated acyl phosphonates, the introduction of bulky alkyl substituents to some extent favored the enantioselectivity . For example, propyl substituted substrates gave higher enantioslecvities than methyl substituted ones (Table 2, entry 5 vs. entry 4 and entry 6 vs. entry 2). This protocol was also broadened to aromatic groups and acceptable results were obtained (Table 2, entries 7 and 8).

R1 R2 Yield (%) b Dr (%) c Ee (%) d Me (2a) Et 82/3aa 8.9:1 83 Me (2b) Me 68/3ab 10.2:1 85 Me (2c) iPr 51/3ac 8.6:1 77 Me (2d) nBu 81/3ad 12.3:1 88 Pr(2e ) nBu 80/3ae 23.7:1 89 Pr (2f) Me 65/3af 17.5:1 93 Ph(2g) Me 71/3ag 4.9:1 74 2-Furyl Me 61/3ah 3.2:1 80 8 (2h) a All reactions were performed with 1a (0.1mmol), 2 (0.4mmol) and 4g (20 mol%) in Et2 O (2 mL). b Yield of isolated product as a diastereoisomeric mixture. c Determined by chiral HPLC. d Enantiomeric excess for major diastereoisomers determined by chiral HPLC analysis. e T he reaction was performed at 10 oC for 10 h. Entry 1 2 3 4 5e 6e 7

Unless noted, reactions were performed with 0.1 mmol of 1a, 0.1 mmol of 2a and 20 mol % catalyst in 2 mL of solvent at room temperature for the specified time. b Yield of isolated product as a diastereoisomeric mixture. c Determined by chiral HPLC. d Enantiomeric excess for major diastereoisomers determined by chiral HPLC. e The reaction was performed at -10 o C. f The reaction was performed at -20 o C. g The reaction was performed at -30 oC.

could improve the yield to 60% while the enantioslectivity decreased sharply to 85% ee (Table 1, entry17). Further increasing the loading of 2a, the yield increased to 82% and the enantioslectivity decreased to 83% ee (Table 1, entry 18).

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Table 2 Scope of asymmetric Michael addition of 3-benzyl-2-oxoindoline 1a to α,β-Unsaturated Acylphosphonatesa

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Entry 1 2 3 4f 5 6f 7 8 9 10 f 11 f 12 13 f 14 15 f 16 17 18 e 19 e 20 21 22

R1 4-MeOC6 H4CH2 (1b) 4-Br C6 H4 CH2 (1c) 3-F C6 H4 CH2 (1d) 2-Cl C6 H4 CH2 (1f) (1g) 3,5-Me2C6 H3CH2(1h) (1i) (1j) (1k) C6 H5 (1l) 4-Me C6 H4 (1m) 4- C6 H4 C6 H4 (1n) 4-Cl C6 H4 (1o) Me (1p) nBu (1q) MeOOCCH2 (1r) EtOOCCH2 (1s) Bn (1t) Bn (1u) Bn (1v) Bn (1w) Bn (1x)

R2 H H H H H

R3 Boc Boc Boc Boc Boc

NuH. MeOH MeOH MeOH MeOH MeOH

Yield (%) b 78/3bd 60/3cd 78/3dd 86/3fd 84/3gd

Dr (%) c 11.8:1 36.5:1 29.2:1 54.9:1 13.8:1

Ee (%) d 85 93 94 98 89

H H H H

Boc Boc Boc Boc

MeOH MeOH MeOH MeOH

61/3hd 75/3id 86/3jd 82/3kd

7.3:1 50.3:1 >99:1 26.2:1

78 98 96 96

H H H H H H H H Me F H H H

Boc Boc Boc Boc Boc Boc Boc Boc Boc Boc Ac Ts CONHPh

EtOH MeOH morpholine MeOH MeOH MeOH MeOH EtOH MeOH MeOH MeOH BnNH2 MeOH

85/3ld 70/3md 75/3nd 73/3od 84/3pd 76/3qd 79/3rd 78/3sd 82/3td 65/3ud 96/3vd 98/3wd 94/3xd

24.8:1 14.8:1 11.4:1 2.0:1 5.7:1 7.8:1 45.7:1 12.1:1 11.1:1 36.1:1 4.3:1 4.9:1 2.9:1

81 79 76 79/69 70 68 93 97 85 93 3 60 35 g

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All reactions were performed with 1a (0.1 mmol), 2 (0.4 mmol) and 4g (20 mol%) in Et2 O (2 mL). b Yield of isolated product as a diastereoisomeric mixture. c Determined by chiral HPLC. d Enantiomeric excess for major diastereoisomers determined by chiral HPLC analysis. e Determined by 1 H NMR. f T he ee vales and yields were determined after deprotection of Boc group. g ee value of minor diastereoisomer.

Subsequently, the scope of the M ichael reactions with respect to various 3-substituted oxindoles 1 and α,β-unsaturated acyl phosphonate 2d was also examined (Table 3). Generally, N-Boc3-substituted oxindoles gave the desired products in moderate to good yields and moderate to excellent ee values with moderate to good dr values (entries 1-19). Various 3-benzyl oxindoles 1b-1h regardless of the electronic and steric properties reacted smoothly with acyl phosphonate 2d, affording the desired products in 6086% yield and 78-98% ee (Table 3, entries 1-6). Gratifyingly, the reactions of 3-hetero-benzyl oxindoles 1i and 1j and 3-naphthylbenzyl oxindole 1k proceeded well to provide 3,3’-disubstituted oxindoles in excellent ee values and good yields (Table 3, entries 7-9). 3-Phenyl oxindoles and 3-alkyl oxindoles were also accommodated albeit with decreased enantioselectivities (Table 3, entries 11-15). M oreover, 3-acetate substituted oxindoles could also be smoothly converted into 3rd and 3sd in excellent ee values (Table 3, entry 16 and 17). We also found that electrondonating and electron-withdrawing substituents could be tolerated on the oxindole’s aromatic ring (Table 3, entry 18 and 19). Furthermore, it was found that the substituents on N atom of oxindoles have obvious negative effects on the enantioselectivities (Table 3, entries 20-22), and N-methyl and no substituted oxindoles gave no corresponding products. Additionally, the use of ethanol or amines instead of methanol as the quenching nucleophiles also led to the corresponding adducts with almost the same level of enantioselectivities (Table 3, entries 10, 12 and 21).

Conclusions

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In summary, we have developed an enantioselective M ichael addition of 3-monsubstituted oxindoles to α,β-unsaturated acyl phosphonates catalyzed by chiral squaramides. A broad range of 3,3'-disubstituted oxindoles bearing adjacent quaternary and tertiary stereogenic centres can be obtained in excellent yields (up to 98%) , diastereo- (up to >99:1 dr) and enantioselectivities (up to 98% ee). This process provides a promising approach for the asymmetric synthesis of structurally complex 3,3'-disubstituted oxindoles. Further mechanistic investigations and the application of the adducts is currently underway in our laboratory.

Acknowledgements

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We are grateful for financial support from the National Natural Science Foundation of China (21372217), the CAS western light program, and the Sichuan Youth Science and Technology Foundation (2013JQ0021 and 2015JQ0041).

References 1. 55

60 35

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Selected examples: (a) J. F. M. da Silva, S. J. Garden and A. C. Pinto, J. Braz. Chem. Soc., 2001, 12, 273; (b) B. S. Jensen, CNS Drug Rev., 2002, 8, 353; (c) H. Lin and S. J. Danishefsky, Angew. Chem., Int. Ed., 2003, 42, 36; (d) C. Marti and E. M. Carreira, Eur. J. Org. Chem ., 2003, 2209; (e) C. V. Galliford and K. A. Scheidt, Angew. Chem., Int. Ed., 2007, 46, 8748; (f) J. J. Badillo, N. V. Hanhan and A. K. Franz, Curr. Opin. Drug Discov. Devel., 2010, 13, 758; (g) G. S. Singh and Z. Y. Desta, Chem. Rev., 2012, 112, 6104. For selected reviews and references cited therein, see: (a) B. M. Journal Name, [year], [vol], 00–00 | 3

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Table 3 Scope of asymmetric Michael addition of 3-monosubstituted oxindoles 1 to α, β-Unsaturated Acylphosphonate 2da

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3.

15

20

25

4. 30

35

40

5.

45

50

55

6.

7. 60

8. 65

9.

70

Trost and M. K. Brennan, Synthesis, 2009, 3003; (b) F. Zhou, Y.-L. Liu and J. Zhou, Adv. Synth. Catal., 2010, 352, 1381; (c) A.-N. R. Alba and R. Rios, Chem. Asian J., 2011, 6, 720; (d) K. Shen, X. Liu, L. Lin, and X. Feng, Chem. Sci., 2012, 3, 327; (e) R. Rios, Chem. Soc. Rev., 2012, 41, 1060; (f) N. R. Ball-Jones, J. J. Badillo and A. K. Franz, Org. Biomol. Chem., 2012, 10, 5165; (g) R. Dalpozzo, G. Bartoli and G. Bencivenni, Chem. Soc. Rev., 2012, 41, 7247; (h) P. Chauhan and S. S. Chimni, Tetrahedron: Asymmetry, 2013, 24, 343; (i) L. Hong and R. Wang, Adv. Synth. Catal., 2013, 355, 1023; (j) D. Cheng, Y. Ishihara, B. Tan and C. F., III. Barbas, ACS Catal., 2014, 4, 743. For selected examples, see: (a) T. Bui, S. Syed and C. F. III. Barbas, J. Am. Chem. Soc., 2009, 131, 8758; (b) Y. Kato, M. Furutachi, Z. Chen, H. Mitsunuma, S. Matsunaga and M. Shibasaki, J. Am. Chem. Soc., 2009, 131, 9168; (c) R. He, S. Shirakawa and K. Maruoka, J. Am. Chem. Soc., 2009, 131, 16620; (d) X. Li, B. Zhang, Z.-G. Xi, S. Luo and J.-P. Cheng, Adv. Synth. Catal., 2010, 352, 416; (e) X.-L. Liu, Z.-J. Wu, X.-L. Du, X.-M. Zhang and W.-C. Yuan, J. Org. Chem., 2011, 76, 4008; (f) M. Ding, F. Zhou, Y.-L. Liu, C.-H. Wang, X.-L. Zhao and J. Zhou, Chem. Sci., 2011, 2, 2035; (g) Y.-Y. Han, Z.-J. Wu, W.-B. Chen, X.-L. Du, X.-M. Zhang and W.-C. Yuan, Org. Lett., 2011, 13, 5064; (h) F. Zhong, X. Dou, X. Han, W. Yao, Q. Zhu, Y. Meng and Y. Lu, Angew. Chem., Int. Ed., 2013, 52, 943; (i) W. Zheng, Z. Zhang, M. J. Kaplan and J. C. Antilla, J. Am. Chem. Soc., 2011, 133, 3339; (j) E. Badiola, B. Fiser, E. Gómez-Bengoa, A. Mielgo, I. Olaizola, I. Urruzuno, J. M. Garcí a, J. M. Odriozola, J. Razkin, M. Oiarbide and C. Palomo, J. Am. Chem. Soc., 2014, 136, 17869. Selected examples: (a) X. Li, Y.-M. Li, F.-Z. Peng, S.-T. Wu, Z.-Q. Li, Z.-W. Sun, H.-B. Zhang and Z.-H. Shao, Org. Lett., 2011, 13, 6160; (b) C. Wang, X. Yang and D. Enders, Chem. Eur. J., 2012, 18, 4832; (c) X. Chen, W. Zhu, W. Qian, E. Feng, Y. Zhou, J. Wang, H. Jiang, Z.-J. Yao and H. Liu, Adv. Synth. Catal., 2012, 354, 2151; (d) M. Retini, G. Bergonzini and P. Melchiorre, Chem. Commun., 2012, 48, 3336; (e) X. Dou, W. Yao, B. Zhou and Y. Lu, Chem. Commun., 2013, 49, 9224; (f) B.-D. Cui, W.-Y. Han, Z.-J. Wu, X.-M. Zhang and W.-C. Yuan, J. Org. Chem., 2013, 78, 8833; (g) X. Dou, B. Zhou, W. Yao, F. Zhong, C. Jiang and Y. Lu, Org. Lett., 2013, 15, 4920; (h) M.-X. Zhao, F.-H. Ji, X.-L. Zhao, Z.-Z. Han and M. Shi. Eur. J. Org. Chem., 2014, 644; (i) L. Zou, X. Bao, Y. Ma, Y. Song, J. Qu and B. Wang, Chem. Commun., 2014, 50, 5760. Selected examples: (a) P. Galzerano, G. Bencivenni, F. Pesciaioli, A. Mazzanti, B. Giannichi, L. Sambri, G. Bartoli, P. Melchiorre, Chem. Eur. J., 2009, 15, 7846; (b) N. Bravo, I. Mon, X. Companyó, A.-N. Alba, A. Moyano, R. Rios, Tetrahedron Lett., 2009, 50, 6624; (c) F. Pesciaioli, X. Tian, G. Bencivenni, G. Bartoli, P. Melchiorre, Synlett, 2010, 1704; (d) M. H. Freund, S. B. Tsogoeva, Synlett, 2011, 503; (e) W. Sun, L. Hong, C. Liu, R. Wang, Tetrahedron: Asymmetry, 2010, 21, 2493; (g) Y.-H. Liao, X.-L. Liu, Z.-J. Wu, X.-L. Du, X.M. Zhang and W.-C. Yuan. Chem. Eur. J., 2012, 18, 6679; (h) X. Wu, Q. Liu, Y. Liu, Q. Wang, Y. Zhang, J. Chen, W. Cao and G. Zhao, Adv. Synth. Catal., 2013, 355, 2701; (i) C. Yang, W. Chen, W. Yang, B. Zhu, L. Yan, C.-H. Tan and Z. Jiang, Chem. Asian J., 2013, 8, 2960. Selected examples: (a) B. M. Trost, J. Xie and J. D. Sieber, J. Am. Chem. Soc., 2011, 133, 20611; (b) J. Chen, Y. Cai and G. Zhao, Adv. Synth. Catal., 2014, 356, 359; (c) T. Wang, W. Yao, F. Zhong, G. H. Pang and Y. Lu, Angew. Chem., Int. Ed., 2014, 53, 2964. Selected examples: (a) Q. Zhu and Y. Lu, Angew. Chem., Int. Ed., 2010, 49, 7753; (b) X. Li, Z.-G. Xi, S. Luo and J.-P. Cheng, Org. Biomol. Chem., 2010, 8, 77; (c) H. J. Lee, S. H. Kang and D. Y. Kim, Synlett, 2011, 1559; (d) X. Dou and Y. Lu, Org. Biomol. Chem., 2013, 11, 5217. T. Zhang, L. Cheng, S. Hameed, L. Liu, D. Wang and Y.-J. Chen, Chem. Commun., 2011, 47, 6644. Selected examples: (a) Y.-H. Liao, X.-L. Liu, Z.-J. Wu, L.-F. Cun, X.-M. Zhang and W.-C. Yuan, Org. Lett., 2010, 12, 2896; (b) L. Li, W. Chen, W. Yang, Y. Pan, H. Liu, C.-H. Tan and Z. Jiang, Chem. Commun., 2012, 48, 5124; (c) X. Yang, C. Wang, Q. Ni and D. Enders, Synthesis, 2012, 16, 2601; (d) J. Zhou, L.-N. Jia, L. Peng, Q.-L. Wang, F. Tian, X.-Y. Xu and L.-X. Wang, Tetrahedron, 2014,

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70, 3478; X. Li, S. Luo and J.-P. Cheng, Chem. Eur. J., 2010, 16, 14290. Selected examples: (a) S.-W. Duan, J. An, J.-R. Chen and W.-J. Xiao, Org. Lett. 2011, 13, 2290; (b) J. Gao, J.-R. Chen,. S.-W. Duan, T.-R. Li, L.-Q. Lu and W.-J. Xiao, Asian J. Org. Chem., 2014, 3, 530. Selected examples: (a) W.-Y. Siau, W. Li, F. Xue, Q. Ren, M. Wu, S. Sun, H. Guo, X. Jiang and J. Wang, Chem. Eur. J., 2012, 18, 9491; (b) J.-S. Yu, F. Zhou, Y.-L. Liu and J. Zhou, Beilstein J. Org. Chem., 2012, 8, 1360; (c) Y. Zhang, X. Hu, S. Li, Y. Liao, W. Yuan and X. Zhang, Tetrahedron, 2014, 70, 2020. For selected examples, see: (a) D. A. Evans, K. A. Scheidt, K. R. Fandrick, H. W. Lam and J. Wu, J. Am. Chem. Soc., 2003, 125, 10780-10781; (b) N. Takenaka, J. P. Abell and H. Yamamoto. J. Am. Chem. Soc., 2007, 129, 742; (c) D. A. Evans, K. R. Fandrick, H.-J. Song, K. A. Scheidt and R. Xu, J. Am. Chem. Soc., 2007, 129, 10029; (d) H. Jiang, M. W. Paixão, D. Monge and K. A. Jørgensen, J. Am. Chem. Soc., 2010, 132, 2775; (e) P. Bachu and T. Akiyama, Chem. Commun., 2010, 46, 4112; (f) T. Liu, Y. Wang, G. Wu, H. Song, Z. Zhou and C. Tang, J. Org. Chem., 2011, 76, 4119-4124. C. Guo, J. Song, S.-W. Luo and L.-Z. Gong, Angew. Chem., Int. Ed., 2010, 49, 5558; and references therein. For selected reviews, see: (a) A. G. Doyle and E. N. Jacobsen, Chem. Rev., 2007, 107, 5713; (b) T. Akiyama, Chem. Rev., 2007, 107, 5744; (c) S. Mukherjee, J. W. Yang, S. Hoffmann and B. List, Chem. Rev., 2007, 107, 5471; (d) U. Scheffler and R. Mahrwald, Chem. Eur. J., 2013, 19, 14346; (e) C. M. R. Volla, I. Atodiresei and M. Rueping, Chem . Rev., 2014, 114, 2390. For selected reviews, see:(a) R. I. Storer, C. Aciro and L. H. Jones, Chem. Soc. Rev., 2011, 40, 2330; (b) J. Alemán, A. Parra, H. Jiang and K. A. Jørgensen, Chem. Eur. J., 2011, 17, 6890; and references therein; For selected examples, see: (a) J. P. Malerich, K. Hagihara and V. H. Rawal, J. Am. Chem. Soc., 2008, 130, 14416; (b) Y. Zhu, J. P. Malerich and V. H. Rawal, Angew. Chem., Int. Ed., 2010, 49, 153; (c) C. Cornaggia, F. Manoni, E. Torrente, S. Tallon and S. J. Connon, Org. Lett., 2012, 14, 1850; (d) S. W. Duan, Y. Li, Y. Y. Liu, Y. Q. Zou, D. Q. Shi and W. J. Xiao, Chem. Commun., 2012, 48, 5160; (e) F. Manoni, C. Cornaggia, J. Murray, S. Tallon and S. J. Connon, Chem. Commun., 2012, 48, 6502; (f) W. Sun, G. Zhu, C. Wu, L. Hong and R. Wang, Chem. Eur. J., 2012, 18, 6737; (g) J. B. Ling, Y. Su, H. L. Zhu, G. Y. Wang and P. F. Xu, Org. Lett., 2012, 14, 1090; (h) K. S. Yang, A. E. Nibbs, Y. E. T ürkmen and V. H. Rawal, J. Am. Chem. Soc., 2013, 135, 16050; (i) H. Zhang, S. Lin and E. N. Jacobsen, J. Am. Chem. Soc., 2014, 136, 16485; (j) F. Manoni and S. J. Connon, Angew. Chem., Int. Ed. 2014, 53, 2628; (k) W. Yang, Y. Yang and D.-M. Du, Org. Lett., 2013, 15, 1190; (l) M.-X. Zhao, H.-L. Bi, R.-H. Jiang, X.-W. Xu and M. Shi, Org. Lett., 2014, 16, 4566; (m) B. Qiao, X. Liu, S. Duan, L. Yan and Z. Jiang, Org. Lett., 2014, 16, 672; (n) W. Sun, L. Hong, G. Zhu, Z. Wang, X. Wei, J. Ni and R. Wang, Org. Lett., 2014, 16, 544. Selected examples: (a) W.-B. Chen, Z.-J. Wu, J. Hu, L.-F. Cun, X.M. Zhang and W.-C. Yuan, Org. Lett., 2011, 13, 2472; (b) Y.-Y. Han, W.-B. Chen, W.-Y. Han, Z.-J. Wu, X.-M. Zhang and W.-C. Yuan, Org. Lett., 2012, 14, 490; (c) Y.-Y. Han, W.-Y. Han, X. Hou, X.-M. Zhang and W.-C. Yuan, Org. Lett., 2012, 14, 4054; (d) X.-L. Liu, W.-Y. Han, X.-M. Zhang and W.-C. Yuan, Org. Lett., 2013, 15, 1246; (e) W. Y. Han, S. W. Li, Z. J. Wu, X. M. Zhang and W. C. Yuan, Chem. Eur. J., 2013, 19, 5551; (f) B.-D. Cui, J. Zuo, J.-Q. Zhao, M.-Q. Zhou, Z.-J. Wu, X.-M. Zhang and W.-C. Yuan, J. Org. Chem., 2014, 79, 5305; (g) B.-D. Cui, Y. You, J.-Q. Zhao, J. Zuo, Z.-J. Wu, X.-Y. Xu, X.-M. Zhang, W.-C. Yuan, Chem. Commun., 2015, 51, 757.

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Organic & Biomolecular Chemistry Accepted Manuscript

Organic & Biomolecular Chemistry

Organocatalytic asymmetric Michael addition of 3-substituted oxindoles to α,β-unsaturated acyl phosphonates for the synthesis of 3,3'-disubstituted oxindoles with chiral squaramides.

A highly enantioselective Michael addition of 3-monosubstituted oxindoles to α,β-unsaturated acyl phosphonates with chiral squaramides as catalysts is...
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