Diastereoselective Deprotonative Metalation of Sugar-Derived Ferrocene Esters Using Mixed Lithium-Cadmium Combinations

The ability of a mixed lithium-cadmium amide to deproto-metallate diastereoselectively several sugar-derived ferrocene esters was studied. The ferrocenecarboxylates generated from alpha-D-glucofuranoses gave the best results, as evidenced after subsequent trapping with iodine. Good chemical yields and diastereoselectivities up to 82% in favor of the S-P stereoisomer were obtained. The use of a different chiral group favored the formation of the R-P stereoisomer, isolated in 34% yield and 98% diastereoselectivity.