Synthesis and structure of the chiral spiro-cyclopropane derivatives

Tandem asymmetric reactions of 1 with nucleophilic alcohols afforded optica lly pure spirocyclopropane derivatives with four stereogenic centers 4a sim ilar to 4e in 64% similar to 88 % yields with d.e. greater than or equal to 98 %. The optically pure compounds 4a similar to 4e were identified on the basis of their analytical data, such as [alpha](D)(20), UV, IR, H-1 NMR, C -13 NMR, MS and elemental analysis. The absolute configuration of the chira l spiro-cyclopropane compound (4a) was established by X-ray crystallography .