Subscriber access provided by UNIVERSITY OF LEEDS
Letter
Nickel-Catalyzed Enantioselective Addition of Styrenes to Cyclic N-Sulfonyl #-Ketiminoesters Ren-Rong Liu, Dan-Jie Wang, Liang Wu, Bin Xiang, Guo-Qi Zhang, Jian-Rong Gao, and Yi-Xia Jia ACS Catal., Just Accepted Manuscript • DOI: 10.1021/acscatal.5b01793 • Publication Date (Web): 02 Oct 2015 Downloaded from http://pubs.acs.org on October 4, 2015
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
ACS Catalysis is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 6
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Catalysis
Nickel-Catalyzed Enantioselective Addition of Styrenes to Cyclic NSulfonyl α-Ketiminoesters Ren-Rong Liu,† Dan-Jie Wang,† Liang Wu ,† Bin Xiang,† Guo-Qi Zhang,‡ Jian-Rong Gao,† and Yi-Xia Jia*† † ‡
College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, China Department of Sciences, John Jay College, the City University of New York, New York, NY 10019, USA
ABSTRACT: Enantioselective addition of styrenes to cyclic N-sulfonyl α-ketiminoesters was developed using the complex of Ni(ClO4)2 with chiral phosphine complex as a catalyst. A range of chiral benzofused 5-membered sultams bearing alkenylated or allylated α-tetrasubstituted amino ester framework were afforded in excellent enantioselectivities (up to 99% ee) as potential biologically active compounds for drug research.
KEYWORDS: Asymmetric catalysis, Nickel, Styrene, Quaternary stereocenter, Sultam Cyclic sulfonamides (sultams) that exhibit broad and important bioactivities have found extensive applications in medicine.1 In particular, benzofused 5-membered sultams have received much attention as they are frequently occurring key structural units of biologically active compounds or drugs, such as 5-HT2 receptor antagonists,2a HIV-1 inhibitors,2b HCV (Hepatitis C virus) NS5b inhibitors,2c and selective CRTh2 antagonists.2d In addition, fused sultams have widespread applications in organic synthesis as protecting groups, chiral auxiliaries, and directed metalation groups.3 Consequently, significant efforts have been devoted to the synthesis of chiral fused 5-membered sultams, including enantioselective addition of organoboron reagents to cyclic N-sulfonyl imines,4 organocatalytic asymmetric annulations of cyclic N-sulfonyl imines,5 and intramolecular C-H bond amination.6 Despite these advances, development of novel and efficient approaches to optically active fused 5-membered sultams is still highly attractive. Chiral allylic amine represents an important structural motif that widely exists in natural products and biologically active molecules.7 Enantioselective addition of olefin moieties to imines offers a straightforward access to chiral allylic amines. So far, documented examples includes the asymmetric addition of reactive alkenylboron reagents to imines4b,8 and the enantioselective aza-Baylis-Hillman reaction of electrondeficient alkenes with imines.9 In spite of its high efficiency and atom economy, the direct addition of simple olefins to imines to furnish chiral allylic amines has remained underdeveloped. Nevertheless, a few recent examples of addition of simple olefins to electron-deficient C=C or C=O bonds have appeared in their racemic versions.10 Herein, we communicate for the first time the direct addition of styrenes to cyclic Nsulfonyl α-ketiminoesters with the complex of Ni(ClO4)2/chiral phosphine11 as a catalyst, leading to allylic amines bearing quaternary stereocenters12 in excellent enantioselectivities (up to 99% ee). Notably, chiral homoallylic amines (up to 95% ee) are afforded when α-methylstyrenes
are used as substrates, which represents the first example of asymmetric ene reaction of ketimines (Scheme 1).13,14 Thus, this protocol provides an efficient access to optically active benzofused 5-membered sultams bearing alkenylated or allylated α-quaternary amino ester framework as potential biologically active compounds for medicinal research.
Scheme 1. Enantioselective addition of styrenes to Nsulfonyl α-ketiminoesters Our study began with the model reaction between cyclic Nsulfonyl α-ketiminoester 1a and styrene 2a. Pleasingly, the initial test revealed that a Cu(OTf)2/bisoxazoline (L1) complex promoted the reaction in DCM while heated in oil-bath at 100 o C for 72 h, affording the desired product 3aa with 67% ee albeit in a low yield (Table 1, entry 1). Other chiral bisoxazoline ligands L2-L4 bearing different substituents on the C4 position of oxazoline ring were then evaluated (entries 2-4). Moderate yield and enantioselectivity were obtained using L2 as a ligand (entry 2), while the use of L3 and L4 led to poor enantiomeric excess (entries 3-4). Although good to excellent enantioselectivities were obtained in the cases of ligands L5 and L6 bearing diphenyl substituents, the yields were not satisfying (entries 5-6). Interestingly, replacing the bisoxazoline ligands with a chiral phosphine ligand (S)-BINAP L7 also resulted in equally high ee value, whereas the yield was even poorer (entry 7). Hence, further catalyst screening was focused on other Lewis acids. Poor results were observed for the complexes of Ni(ClO4)2·6H2O with chiral bisoxazolines L1 and L5 (entries 8-9). To our delight, however, both the reactivity and selectivity were remarkably improved when Ni(ClO4)2·6H2O/L7 complex was used as a catalyst. Thus, the
ACS Paragon Plus Environment
ACS Catalysis
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 2 of 6
reaction was complete in 24 h to afford the desired product in 73% yield and 98% ee (entry 10). Comparable results were afforded for anhydrous Ni(ClO4)2 (entry 11). Surprisingly, Ni(OTf)2 was inactive to the reaction (entry 12). Subsequent investigation on solvent effect showed that the reaction was fully suppressed in THF or CH3CN, and poor yield was obtained in CHCl3 (entries 13-15). Moreover, the reaction could occur at 80 oC to furnish 3aa in a slightly lower yield and with 99% ee (entry 16). Notably, slightly lower enantioselectivity was found with 5 mol% of catalyst loading despite a longer reaction time was required to ensure a reasonable yield (entry 17).
and the results were listed in Table 2. All the reactions proceeded smoothly to afford the desired products 3 in excellent enantioselectivities (92-99% ee). Both electron-withdrawing and electron-donating substituents, such as halides, CF3, OCF3, OMe, and alkyl groups, attached on the C5-C7 position of N-sulfonyl α-ketiminoesters were found to be tolerant to the corresponding reactions, giving the expected products in modest to good yields, showing a broad scope of the reaction. Notably, naphthofused sultam 3la was also isolated in good yields and excellent enantioselectivities. Moreover, good yields and excellent enantioselectivities were obtained for the substrates bearing a variety of ester groups (Me, iPr, or nBu).
Table 1. Optimization of the reaction conditionsa
Table 2. Substrate scope of N-sulfonyl α-ketiminoestersa
entry
LA
L*
solvent
Yield (%)b
ee (%)c
1
Cu(OTf)2
L1
DCM
45
67
2
Cu(OTf)2
L2
DCM
76
73
3
Cu(OTf)2
L3
DCM
60
25
4
Cu(OTf)2
L4
DCM
70
4
5
Cu(OTf)2
L5
DCM
52
92
6
Cu(OTf)2
L6
DCM
50
84
7
Cu(OTf)2
L7
DCM
10
90
8
Ni(ClO4)2·6H2O
L1
DCM
14
19
9
Ni(ClO4)2·6H2O
L5
DCM
22
5
10
Ni(ClO4)2·6H2O
L7
DCM
73
98
11
Ni(ClO4)2
L7
DCM
71
98
12
Ni(OTf)2
L7
DCM
11
ndd
13
Ni(ClO4)2·6H2O
L7
CHCl3
25
ndd
14
Ni(ClO4)2·6H2O
L7
CH3CN
NR
--
15
Ni(ClO4)2·6H2O
L7
THF
NR
--
16e
Ni(ClO4)2·6H2O
L7
DCM
65
99
f
Ni(ClO4)2·6H2O
L7
DCM
68
96
17
a
Reactions conditions: 0.2 mmol 1a, 0.4 mmol 2a, 10 mol% Lewis acid (LA), 12 mol% ligand (L*), and 2.0 mL solvent in a sealed Schlenk tube at 100 oC (temperature of oil bath); 72 h for entries 1-7; 24 h for entries 8-16. bIsolated yield. cDetermined by chiral HPLC. dNot detected. eAt 80 oC. fNi(ClO4)2·6H2O (5 mol%) and L7 (6 mol%) for 60 h.
Having established the optimal conditions, the scope of substrates was then explored. A range of cyclic N-sulfonyl αketiminoesters were examined in the reactions with styrene
a
Reactions conditions: 0.2 mmol 1, 0.4 mmol 2a, 10 mol% Ni(ClO4)2·6H2O, 12 mol% L7, and 2.0 mL DCM in a sealed Schlenk tube at 100 oC (temperature of oil bath) for 24 h, isolated yield, ee was determined by chiral HPLC.
Styrene derivatives were also examined under the optimal reaction conditions. As shown in Table 3, the reactions of styrenes having electron-donating substituents on the benzene ring proceeded well and offered products 3 in moderate to good yields and excellent enantioselectivities (Table 3, products 3ab, 3ac and 3af-3ai). However, relatively lower yield was obtained for product 3ag bearing a 3-OMe group. Styrenes containing electron-withdrawing groups were confirmed to be relatively more challenging substrates and a higher catalyst loading was required to gain acceptable yields for products 3ad and 3ae, although the enantioselectivities were very good. Gratifyingly, although no reaction was observed for αsubstituted styrene, 1H-indene was well compatible with the reaction, affording product 3aj in 68% yield and 95% ee. To be noted, aliphatic olefins showed almost no reactivity under the same reaction conditions.
ACS Paragon Plus Environment
Page 3 of 6
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Catalysis
Table 3. Substrate scope of styrenes
Ni(ClO4)2 slightly increased enantioselectivity (77%), and the reaction of isopropyl ester substrate 1n delivered the product in 84% ee. The enentioselectivity was further improved to 92% when (S)-Segphos L8 was used as a ligand. Subsequently, a series of N-sulfonyl α-ketiminoesters and αmethylstyrenes were tested under these conditions and the results were listed in Table 4. Enantioselectivities were generally excellent (90-95%) for the reactions of N-sulfonyl αketiminoesters bearing either electron-donating or electronwithdrawing substituents at C3-C5 position on the benzene ring. However, the yields were influenced unfavorablely for those bearing electron-withdrawing substituents (7a-7d vs 7e7h). Substituent effect of α-methylstyrenes was also evaluated, and the reactions afforded the desired products 7i-7n in excellent enantioselectivities with modest to good yields. The results showed broad substrate scope of the asymmetric ene reaction of N-sulfonyl α-ketiminoesters.
a
Table 4. Substrate scope of ene reactiona
a
Reactions conditions: 0.2 mmol 1a, 0.4 mmol 2, 10 mol% Ni(ClO4)2·6H2O, 12 mol% L7, and 2.0 mL DCM in a sealed Schlenk tube at 100 oC (temperature of oil bath) for 24-72 h, isolated yield, ee was determined by chiral HPLC; For products 3ad and 3ae, 25 mol% Ni(ClO4)2·6H2O and 30 mol% L7 were used.
Scheme 2. Optimization of ene reaction between N-sulfonyl α-ketiminoester and α-methylstyrene As shown in Scheme 2, whenα-methylstyrene 4a was tested as a substrate in this reaction, homoallylic amide 5 was isolated in good yield and with modest ee (75%), while the expected addition product 6 was isolated in very poor yield but with 91% ee. The difference observed in ee values implied different reaction pathways for the formation of compounds 5 and 6. The formation of compound 6 was proposed to proceed through a benzylic carbocationic intermediate generation and subsequent β-proton elimination (an aza-Prins mechanism), however, product 5 was likely formed through a pericyclic process (ene reaction pathway). To the best of our knowledge, the asymmetric ene reaction of ketimine has remained undocumented.13,14 Therefore, optimization of the ene reaction was conducted to improve the enantioselectivity. Dehydrated
a Reactions conditions: 0.2 mmol 1, 0.6 mmol 4, 10 mol% Ni(ClO4)2, 12 mol% L8, and 2.0 mL DCM in a sealed Schlenk tube at 100 oC (temperature of oil bath) for 20-40 h, isolated yield, ee was determined by chiral HPLC.
To confirm the scalability of the present protocol, the scaleup reaction of N-sulfonyl α-ketiminoester 1a with styrene was carried out and product 3aa was readily isolated in 72% yield and 95% ee (Scheme 3).15 Transformation of 3aa to compound 9 were then conducted (Scheme 4). Pd/C-catalyzed hydrogenation of 3aa in methanol at room temperature afforded 8 in 97% ee. Subsequent treatment of 8 with BzCl in ether led to compound 9 in 75% yield and with complete preservation of enantiopurity. The absolute configuration of 9 was then determined to be R based on its X-ray analysis, which conversely implied the R configuration of product 3aa.
ACS Paragon Plus Environment
ACS Catalysis
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Scheme 3. The scale-up reaction of 1a with 2
Scheme 4. Transformation of 3aa to 9 and determination of the absolute configuration
In summary, we have developed a highly enantioselective nickel-catalyzed addition of styrenes to N-sulfonyl αketiminoester. A broad scope of optically active benzofused 5membered sultams containing alkenylated or allylated αquaternary amino ester framework are obtained, which are anticipated to be potential bioactive compounds or drug precursors for medicinal applications. Meanwhile, either the direct addition of styrenes to imines or the ene reaction of ketimines provide a novel and efficient route to chiral allylic or homoallylic amine derivatives, which significantly expanded our understanding of this important class of C-C bond forming reactions.
ASSOCIATED CONTENT Supporting Information. Full experimental and characterization data, including 1H, and 13C NMR for all the new compounds, chiral HPLC spectra for the products, and crystal data are available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION Corresponding Author
[email protected] Notes The authors declare no competing financial interests.
ACKNOWLEDGMENT We are grateful for the generous financial support by the National Natural Science Foundation of P. R. China (21372202), the New Century Excellent Talents in University (NCET-12-1086), and Zhejiang Natural Science Fund for Distinguished Young Scholars (LR14B020001).
REFERENCES
Page 4 of 6
(1) For reviews, see: (a) A.-S. S. Hamad Elgazwy, Tetrahedron 2003, 59, 7445–7463. (b) Majumdar, K. C.; Mondal, S. Chem. Rev. 2011, 111, 7749–7773. (2) (a) Malleron, J. L.; Comte, M. T.; Gueremy, C.; Peyronel, J. F.; Truchon, A.; Blanchard, J. C.; Doble, A.; Piot, O.; Zundel, J. L.; Huon, C.; Martin, B.; Mouton, P.; Viroulaud, A.; Allam, D.; Betschart, J. J. Med. Chem. 1991, 34, 2477–2483. (b) Zhuang, L.; Wai, J. S.; Embrey, M. W.; Fisher, T. E.; Egbertson, M. S.; Payne, L. S.; Guare, J. P.; Vacca, J. P.; Hazuda, D. J.; Felock, P. J.; Wolfe, A. L.; Stilmock, K. A.; Witmer, M. V.; Moyer, G.; Schleif, W. A.; Gabryelski, L. J.; Leonard, Y. M.; Lynch, J. J.; Michelson, S. R.; Young, S. D. J. Med. Chem. 2003, 46, 453–456. (c) Hendrick, R. T.; Spencer, S. R.; Blake, J. F.; Fell, J. B.; Fischer, J. P.; Stengel, P. J.; Leveque, V. J. P.; LePogam, S.; Rajyaguru, S.; Najera, I.; Joesy, J. A.; Swallow, S. Bioorg. Med. Chem. Lett. 2009, 19, 410–414. (d) Tumey, L. N.; Robarge, M. J.; Gleason, E.; Song, J.; Murphy, S. M.; Ekema, G.; Doucette, C.; Hanniford, D.; Palmer, M.; Pawlowski, G.; Danzig, J.; Loftus, M.; Hunady, K.; Sherf, B.; Mays, R. W.; Krongrad, A. S.; Brunden, K. R.; Bennani, Y. L.; Harrington, J. J. Bioorg. Med. Chem. Lett. 2010, 20, 3287–3290. (3) (a) Wills, M.; Oppolzer, W.; Kelly, M. J.; Signer, M.; Blagg, J. Tetrahedron Lett. 1990, 31, 5015–5018. (b) Ahn, K. H.; Ham, C.; Kim, S.-K.; Cho, C.-W. J. Org. Chem. 1997, 62, 7047–7048. (c) Ahn, K. H.; Baek, H.-H.; Lee, S. J.; Cho, C.-W. J. Org. Chem. 2000, 65, 7690–7696. (4) (a) Nishimura, T.; Noishiki, A.; Tsui, G. C.; Hayashi, T. J. Am. Chem. Soc. 2012, 134, 5056–5059. (b) Luo, Y.; Carnell, A. J.; Lam, H. W. Angew. Chem. Int. Ed. 2012, 51, 6762–6766. (c) Wang, H.; Jiang, T.; Xu, M.-H. J. Am. Chem. Soc. 2013, 135, 971–974. (d) G. Yang, W. Zhang, Angew. Chem. Int. Ed. 2013, 52, 7540–7544. (e) Nishimura, T.; Ebe, Y.; Fujimoto, H.; Hayashi, T. Chem. Commun. 2013, 49, 5504–5506. (f) Hepburn, H. B.; Chotsaeng, N.; Luo, Y.; Lam, H. W. Synthesis 2013, 45, 2649–2661. (g) Jiang, C.; Lu, Y.; Hayashi, T. Angew. Chem. Int. Ed. 2014, 53, 9936–9939. (h) Hepburn, H. B.; Lam, H. W. Angew. Chem. Int. Ed. 2014, 53, 11605–11610. (5) (a) Rommel, M.; Fukuzumi, T.; Bode, J. W. J. Am. Chem. Soc. 2008, 130, 17266–17267. (b) Chiang, P.-C..; Rommel, M.; Bode, J. W. J. Am. Chem. Soc. 2009, 131, 8714–8718. (c) Ma, C.; Gu, J.; Teng, B.; Zhou, Q.-Q.; Li, R.; Chen, Y.-C. Org. Lett. 2013, 15, 6206–6209. (d) Feng, X.; Zhou, Z.; Ma, C.; Yin, X.; Li, R.; Dong, L.; Chen, Y.-C. Angew. Chem. Int. Ed. 2013, 52, 14173–14176. (e) Gu, J. Ma, C.; Li, Q.-Z.; Du, W.; Chen, Y.-C. Org. Lett. 2014, 16, 3986–3989. (f) Yin, X.; Zheng, Y.; Feng. X.; Jiang, K.; Wei, X.-Z.; Gao, N.; Chen. Y.-C. Angew. Chem. Int. Ed. 2014, 53, 6245–6248. (g) An, Q.; Shen, J.; Butt, N.; Liu, D.; Liu, Y.; Zhang, W. Org. Lett. 2014, 16, 4496–4499. (6) (a) Ichinose, M.; Suematsu, H.; Yasutomi, Y.; Nishioka, Y.; Uchida, T.; Katsuki, T. Angew. Chem. Int. Ed. 2011, 50, 9884–9887. (b) McIntosh, J. A.; Coelho, P. S.; Farwell, C. C.; Wang, Z. J.; Lewis, J. C.; Brown, T. R.; Arnold, F. H. Angew. Chem. Int. Ed. 2013, 52, 9309–9312. (7) (a) Johannsen, M.; Jørgensen, K. A. Chem. Rev. 1998, 98, 1689–1708. (b) Trost, B. M.; Van Vraken, D. L. Chem. Rev. 1996, 96, 395–422. (c) Trost, B. M.; Crawley, M. L. Chem. Rev. 2003, 103, 2921–2944. (d) Lu, Z.; Ma, S. Angew. Chem. Int. Ed. 2008, 47, 258– 297. (h) Wei, F.; Huang, H.-Y.; Zhong, N.-J.; Gu, C.-L.; Wang, D.; Liu, L. Org. Lett. 2015, 17, 1688–1691. (i) Zhang, S.; Li, L.; Hu, Y.; Zha, Z.; Wang, Z.; Loh, T.-P. Org. Lett. 2015, 17, 1050–1053. (j) Wu, L.; Liu, R.-R.; Zhang, G.; Wang, D.-J.; Wu, H.; Gao, J.; Jia, Y.-X. Adv. Synth. Catal. 2015, 357, 709–713. (8) (a) Lou, S.; Schaus, S. E. J. Am. Chem. Soc. 2008, 130, 6922– 6923. (b) Brak, K.; Ellman, J. A. J. Am. Chem. Soc. 2009, 131, 3850– 3851. (9) Selected recent reviews: (a) Basavaiah, D.; Satyanarayana, T.; Rao, A. J. Chem. Rev. 2003, 103, 811–892. (b) Masson, G.; Housseman, C.; Zhu, J. Angew. Chem. Int. Ed. 2007, 46, 4614–4618. (c) Basavaiah, D.; Veeraraghavaiah, G. Chem. Soc. Rev. 2012, 41, 68–78. (d) Wei, Y.; Shi, M. Chem. Rev. 2013, 113, 6659–6690.
ACS Paragon Plus Environment
Page 5 of 6
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Catalysis
(10) (a) Okamoto, K.; Tamura, E.; Ohe, K. Angew. Chem. Int. Ed. 2013, 52, 10639–10643. (b) Cui, L.; Zhu, Y.; Luo, S.; Cheng, J.-P. Chem. Eur. J. 2013, 9481–9484. (c) Qin, Y.; Lv, J.; Luo, S.; Cheng, J.-P. Org. Lett. 2014, 16, 5032–5035. (d) Lv, J.; Zhong, X.; Luo, S. Chem. Eur. J. 2014, 20, 8293–8296. (e) Qian, B.; Zhang, G.; Ding, Y.; Huang, H. Chem. Commun. 2013, 49, 9839–9841. (11) Ni(ClO4)2 has been proved to be efficient catalyst in asymmetric catalysis. For review, see: (a) Dalpozzo, R.; Bartoli, G.; Sambri, L.; Melchiorre, P. Chem. Rev. 2010, 110, 3501–3551. For selected recent examples: (b) Kanemasa, S.; Kanai, T. J. Am. Chem. Soc. 2000, 122, 10710–10711. (c) Kennosuke, I.; Kanemasa, S. J. Am. Chem. Soc. 2002, 124, 13394–13395. (d) Shibata, N.; Kohno, J.; Takai, K.; Ishimaru, T.; Nakamura, S.; Toru, T.; Kanemasa, S. Angew. Chem. Int. Ed. 2005, 44, 4204–4207. (e) Zhou, Y.-Y.; Wang, L.J.; Li, J.; Sun, X.-L.; Tang, Y. J. Am. Chem. Soc. 2012, 134, 9066– 9069. (12) For recent reviews on quaternary stereocenters: (a) Christoffers, J.; Baro, A. Adv. Synth. Catal. 2005, 347, 1473–1482. (b) Bella, M.; Gasperi, T. Synthesis 2009, 1583–1614. (c) Quasdorf, K. W.; Overman, L. E. Nature 2014, 516, 181–191. (13) For reviews of asymmetric ene reaction, see: (a) Mikami, K.; Shimizu, M. Chem. Rev. 1992, 92, 1021–1050. (b) Clarke, M. L.; France, M. B. Tetrahedron 2008, 64, 9003–9031. For recent selected examples of asymmetric carbonyl-ene reaction: (c) Mikami, K.; Terada, M.; Nakai, T. J. Am. Chem. Soc. 1990, 112, 3949–3954. (d) Ding,
K.; Yuan, Y.; Zhang, X. Angew. Chem. Int. Ed. 2003, 42, 5478–5480. (e) Hutson, G. E.; Dave, A. H.; Rawal, V. H. Org. Lett. 2007, 9, 3869–3872. (f) Zhao, J. F.; Tsui, H. Y.; Wu, P. J.; Lu, J.; Loh, T. P. J. Am. Chem. Soc. 2008, 130, 16492–16493. (g) Evans, D. A.; Wu, J. J. Am. Chem. Soc. 2005, 127, 8006–8007. (h) Grachan, M. L.; Tudge, M. T.; Jacobsen, E. N. Angew. Chem. Int. Ed. 2008, 47, 1469–1472. (i) Rueping, M.; Theissmann, T.; Kuenkel, A.; Koenigs, R. M. Angew. Chem. Int. Ed. 2008, 47, 6798–6801. (j) Terada, M.; Soga, K.; Momiyama, N. Angew. Chem. Int. Ed. 2008, 47, 4122–4125. (k) Zheng, K.; Shi, J.; Liu, X.; Feng, X. J. Am. Chem. Soc. 2008, 130, 15770–15771. (l) Truong, P. M.; Zavalij, P. Y.; Doyle, M. P. Angew. Chem. Int. Ed. 2014, 53, 6468–6472. (14) For enantioselective ene reaction of aldimines, see: (a) Drury, W. J.; Ferraris, D. III; Cox, C.; Young, B.; Lectka, T. J. Am. Chem. Soc. 1998, 120, 11006–11007. (b) Yao, S.; Fang, X.; Jørgensen, K. A. Chem Commun. 1998, 2547–2548. (c) Ferraris, D.; Young, B.; Cox, C.; Dudding, T.; Drury, W. J.; Ryzhkov, L. III; Taggi, A. E.; Lectka, T. J. Am. Chem. Soc. 2002, 124, 67–77. (d) Caplan, N. A.; Hancock, F. E.; Bulman Page, P. C.; Hutchings, G. J. Angew. Chem. Int. Ed. 2004, 43, 1685–1688. (e) Terada, M.; Machioka, K.; Sorimachi, K. J. Am. Chem. Soc. 2007, 129, 10336–10337. (f) Terada, M.; Machioka, K.; Sorimachi, K. Angew. Chem. Int. Ed. 2009, 48, 2553–2556. (15) The scale-up reaction was carried out in a three-necked flask containing condenser under N2 atmosphere in oil-bath at 100 oC.
ACS Paragon Plus Environment
ACS Catalysis
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 6 of 6
Nickel-Catalyzed Enantioselective Addition of Styrenes to Cyclic N-Sulfonyl α-Ketiminoesters
ACS Paragon Plus Environment
6
