Synfacts 2007(8): 0827-0827  
DOI: 10.1055/s-2007-968727
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Enantioselective Carbonyl Ylide Formation/1,3-Dipolar Cycloaddition

Contributor(s): Mark Lautens, Praew Thansandote
H. Tsutsui, N. Shimada, T. Abe, M. Anada, M. Nakajima, S. Nakamura, H. Nambu, S. Hashimoto*
Hokkaido University, Sapporo, Japan
Further Information

Publication History

Publication Date:
24 July 2007 (online)

Significance

Complementary to previous reports on related enantioselective carbonyl ylide cycloadditions (M. P. Doyle, D. C. Forbes Chem. Rev. 1998, 98, 911; H. Suga, K. Inoue, S. Inoue, A. Kakehi J. Am. Chem. Soc. 2002, 124, 14836), this communication reports an enantioselective intermolecular 1,3-dipolar cyclo­addition of a carbonyl ylide and an aromatic aldehyde as the dipolarophile. The reaction is catalyzed by a chiral dirhodium(II) catalyst and gives exclusively the exo product. The highest ee values are seen for electron-withdrawing benzaldehyde dipolarophiles. The enantioselectivity is also dependent on the substitution pattern at the ylide carbonyl (best with an aromatic ring), substitution at the α-position of the carbonyl ylide (best as H), and the length of the tether between the carbonyl and di­azo ester components of the ylide (best with a one-carbon tether).