An optically active vinylic sulfoxide is stereoselectiviely transformed into a chiral cyclopropane by means of a Michael addition reaction with an allyl Grignard reagent, and using this novel cyclopropanation, assmmetric construction of a spiro [4.5] decane is achieved.
We investigated the stereoselective construction of the C2 stereogenic center of the spiro[4.5]decane skeleton present in the spirovetivanes, spirolaurane, and spiroaxanes, and succeeded in synthesizing 2α- and 2β-substituted 6-spiro[4.5]decanones with diastereoselectivity by employing n-Bu3-SnH-mediated spiroannulation of the alkylmercury chloride, and Pd(II)-mediated spiroannulation followed by catalytic hydrogenation of the resulting unsaturated ester, respectively.