ORGANIC LETTERS
Chiral Amino Alcohol-Mediated Asymmetric Conjugate Addition of Arylalkynes to Nitroolefins
2005 Vol. 7, No. 12 2369-2371
Mitsuaki Yamashita, Ken-ichi Yamada, and Kiyoshi Tomioka* Graduate School of Pharmaceutical Sciences, Kyoto UniVersity, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
[email protected] Received March 25, 2005
ABSTRACT
The asymmetric reaction of nitroolefins with arylalkynes was mediated by dimethylzinc (or diethylzinc) and (1R,2R)-2-(dimethylamino)-1,2diphenylethanol in toluene to provide the corresponding conjugate alkynylation products with high enantiomeric excess of up to 99% in good yields. The presence of 0.03 equiv of galvinoxyl improved the reaction yield.
The asymmetric addition of alkynes to an electron-deficient double bond has been the recent focus of asymmeric reactions.1 Aldehydes,2-5 ketones,6-8 and imines9-12 are electrophiles that have been well documented by many
groups. On the other hand, R,β-unsaturated carbonyl compounds or their congeners are acceptors that have seldom accomplished high enantioselectivity.13-15 The catalytic asymmetric conjugate alkynylation of enones recently re-
(1) Review: (a) Cozzi, P. G.; Hilgraf, R.; Zimmermann, N. Eur. J. Org. Chem. 2004, 4095-4105. (b) Pu, L. Tetrahedron 2003, 59, 9873-9886. (2) Lithium acetylide: Mukaiyama, T.; Suzuki, K.; Soai, K.; Sato, T. Chem. Lett. 1979, 447-448. (3) Alkynylborane: Corey, E. J.; Cimprich, K. A. J. Am. Chem. Soc. 1994, 116, 3151-3152. (4) Recent catalytic addition of zinc acetylide using dialkylzinc: (a) Kang, Y.-F.; Liu, L.; Wang, R.; Yan, W.-J.; Zhou, Y.-F. Tetrahedron: Asymmetry 2004, 15, 3155-3159. (b) Dahmen, S. Org. Lett. 2004, 6, 2113-2116. (c) Li, Z.-B.; Pu, L. Org. Lett. 2004, 6, 1065-1068. (d) Marshall, J. A.; Bourbeau, M. P. Org. Lett. 2003, 5, 3197-3199. (e) Kamble, R. M.; Singh, V. K. Tetrahedron Lett. 2003, 44, 5347-5349. (f) Li, X.-S.; Lu, G.; Kwok, W. H.; Chan, A. S. C. J. Am. Chem. Soc. 2002, 124, 12636-12637. (g) Braga, A. L.; Appelt, H. R.; Silveira, C. C.; Wessjohann, L. A.; Schneider, P. H. Tetrahedron 2002, 58, 10413-10416. (5) Catalytic addition of zinc acetylide using Zn(OTf)2: (a) Jiang, B.; Chen, Z.; Xiong, W. J. Chem. Soc., Chem. Commun. 2002, 1524-1525. (b) Anand, N. K.; Carreira, E. M. J. Am. Chem. Soc. 2001, 123, 96879688. (c) Frantz, D. E.; Fassler, R.; Carreira, E. M. J. Am. Chem. Soc. 2000, 122, 1806-1807. (6) Lithium acetylide: (a) Scharpwinkel, K.; Matull, S.; Schafer, H. J. Tetrahedron: Asymmetry 1996, 7, 2497-2500. (b) Thompson, A. S.; Corley, E. G.; Huntington, M. F.; Grabowski, E. J. J. Tetrahedron Lett. 1995, 36, 8937-8940. (7) Zinc acetylide: Tan, L.; Chen, C.-Y.; Tillyer, R. D.; Grabowski, E. J. J.; Reider, P. J. Angew. Chem., Int. Ed. 1999, 38, 711-713.
(8) Catalytic addition of zinc acetylide: (a) Liu, L.; Wang, R.; Kang, Y.-F.; Chen, C.; Xu, Z.-Q.; Zhou, Y.-F.; Ni, M.; Cai, H.-Q.; Gong, M.-Z. J. Org. Chem. 2005, 70, 1084-1086. (b) Kang, Y.-F.; Liu, L.; Wang, R.; Zhou, Y.-F.; Yan, W.-J. AdV. Synth. Catal. 2005, 347, 243-247. (c) Zhou, Y.-F.; Wang, R.; Xu, Z.-Q.; Yan, W.-J.; Liu, L.; Kang, Y.-F.; Han, Z.-J. Org. Lett. 2004, 6, 4147-4149. (d) Liu, L.; Kang, Y.-F.; Wang, R.; Zhou, Y.-F.; Chen, C.; Ni, M.; Gong, M.-Z. Tetrahedron: Asymmetry 2004, 15, 3757-3761. (e) Saito, B.; Katsuki, T. Synlett 2004, 1557-1560. (f) Lu, G.; Li, X.; Jia, X.; Chan, W. L.; Chan, A. S. C. Angew. Chem., Int. Ed. 2003, 42, 5057-5058. (g) Cozzi, P. G. Angew. Chem., Int. Ed. 2003, 42, 2895-2898. (9) Addition of lithium acetylide to ketimine: Huffman, M. A.; Yasuda, N.; DeCamp, A. E.; Grabowski, E. J. J. J. Org. Chem. 1995, 60, 15901594. (10) Catalytic addition of copper acetylide to enamine: Koradin, C.; Polborn, K.; Knochel, P. Angew. Chem., Int. Ed. 2002, 41, 2535-2538. (11) Catalytic addition of copper acetylide: (a) Kno¨pfel, T. F.; Aschwanden, P.; Ichikawa, T.; Watanabe, T.; Carreira, E. M. Angew. Chem., Int. Ed. 2004, 43, 5971-5973. (b) Benaglia, M.; Negri, D.; Dell’Anna, G. Tetrahedron. Lett. 2004, 45, 8705-8708. (c) Gommermann, N.; Koradin, C.; Polborn, K.; Knochel, P. Angew. Chem., Int. Ed. 2003, 42, 5763-5766. (d) Wei, C.; Li, C. W. J. Am. Chem. Soc. 2002, 124, 5638-5639. (12) Catalytic addition of zinc acetylide: Traverse, J. F.; Hoveyda, A. H.; Snapper, M. L. Org. Lett. 2003, 5, 3273-3275. (13) Asymmetric conjugate addition of chiral boron acetylide: Chong, J. M.; Shen, L.; Taylor, N. J. J. Am. Chem. Soc. 2000, 122, 1822-1823.
10.1021/ol050643p CCC: $30.25 Published on Web 05/10/2005
© 2005 American Chemical Society
ported by Corey and Chong is the exception.16 We describe herein that arylalkynes undergo conjugate addition reaction with nitroolefins to provide the corresponding alkynylation adducts with high enantioselectivities of up to 99% ee. Our approach began with the application of the chiral ligand-controlled asymmetric conjugate addition reaction of aryllithiums with nitroolefins.17,18 The reaction of lithiated trityl ether of propargyl alcohol 2a with nitroolefin 1a in the presence of a tridentate chiral amino ether ligand 3a in toluene, however, gave the addition product 4a with a marginal ee of 7% in 96% yield. Reaction of heteroaggregated lithium acetylide of 2a with a chiral amino alcohol 3b, the starting material for the preparation of 3a,17b was not successful, giving 4a with 4% ee in 92% yield. Promising results were obtained by changing the metal from lithium to zinc (Table 1). The reaction of 1.5 equiv of
Table 1. Amino Alcohol 3b-Mediated Asymmetric Conjugate Addition of 2b to 1a Giving 4b
entry
2b (equiv)
3b (equiv)
Me2Zn (equiv)
1 2c 3 4d 5d,e 6
1.5 1.5 3 3 3 3
1.5 1.5 3 3 3 0
1.5 1.5 3 3 3 3
temp (°C)
time (h)
yield (%)a
ee (%)b
50 rt 50 rt rt 50
24 120 10 30 30 15
39 52 66 83 74
