Diastereoselective synthesis of cyclopropanes with multiple sulfur substitution. X-Ray molecular structures of phenylsulfonyl-substituted cyclopropanes
Reaction of 1-phenylsulfonyl-1-phenylthioalkenes 3 with lithiated phenyl phenylthiomethyl sulfone 4 gave 1-phenylsulfonyl-1, 2-bis(phenylthio)cyclopropanes 5 as single diastereoisomers in good yield. The relative stereochemistry of the cyclopropane 5a was established by an X-ray crystal-structure determination. Oxidation of the cyclopropane 5a with m-chloroperbenzoic acid gave the tris-sulfone 6 which, either on heating or on treatment with base, was converted efficiently into the epimeric tris-sulfone 7. The structures of both of these sulfones were established by X-ray crystal-structure determinations. Reaction of lithiated phenyl phenylthiomethyl sulfone with the 1-(phenylthio)vinylsulfoximide 9 gave the cyclopropanes 11a and 11b as a 3:1 mixture of diastereoisomers. The structure of the major product 11a was established by an X-ray crystal-structure determination. Reaction of lithiated phenyl phenylthiomethyl sulfone with the simple vinylsulfoximide 10b gave the 1-phenylsulfonyl-1-phenylthiocyclopropane 12 in moderate yield, and the structure was determined by X-ray crystallography. The structural parameters of the cyclopropanes are compared, and asymmetry parameters are reported.