Rh(I)-Catalyzed Stereoselective Carbocyclization of Alkynals and Alkenes

K. Tanaka; Y. Hagiwara; M. Hirano

doi:10.1055/s-2006-949436

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Synfacts 2006(11): 1148-1148
DOI: 10.1055/s-2006-949436

Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions

Rh(I)-Catalyzed Stereoselective Carbocyclization of Alkynals and Alkenes

Contributor(s): Mark Lautens, Andrew Martins
K. Tanaka*, Y. Hagiwara, M. Hirano
Tokyo University of Agriculture and Technology, Japan

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Publication History

Publication Date:
24 October 2006 (online)

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Significance

In the presence of a Rh(I)/phosphine catalyst system, aliphatic and aromatic alkynals undergo carbocyclization with an external alkene to generate chiral alkylidene cyclohexanones in poor to excellent yield, and with excellent diastereo- or enantioselectivities. Alkynals with a substitutent at R¹ afford products with excellent syn selectivity, whereas substitution at R² displayed excellent anti selectivity. When (R,R)-WalPhos was used as ligand, products were obtained in high ee. Overall, aromatic alkynals afforded higher yields of product over aliphatic alkynals, with comparable ee values for both cases.