Diastereoselective synthesis carbon-hydrogen bond activation

The 1,2-disubstituted 2-cyclopropenecarboxylates are useful for the synthesis of optically active cyclopropane building blocks containing an all-carbon quaternary stereogenic center.Treatment with LiAlUj produced fra/w-cyclopropane derivative as the sole product through a sequential reduction of the ester moiety and hydroalumination of the double bond (eq 3). Alternatively, catalytic hydrogenation proceeded from the opposite face to the 2,4-dimethyl-3-pentyl ester moiety and subsequent reduction with DIBAL-H gave cis-cyclopropane product with virtually complete diastereoselectivity. 

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