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Synfacts 2006(11): 1148-1148  
DOI: 10.1055/s-2006-949436
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

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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Publikationsverlauf

Publikationsdatum:
24. Oktober 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.