A Practical Synthesis of Polyhalomethyllithium-Carbonyl Adducts

Abstract

Abstract The title adducts are produced upon treatment of a mixture of polyhalomethane and a carbonyl compound with a hindered lithium amide. The kinetically controlled, selective lithiation of the halide enables us to avoid a troublesome procedure involving preformed lithium carbenoid. The halide components examined are dichloromethane, dibromomethane, diiodomethane, chloroform, and bromoform, while the carbonyl ones are ubiquitous ketones and nonanal. A gem-dichloroallyllithium is generated similarly from 3,3-dichloropropene and, furthermore, the procedure is successfully extended to the Darzens-type reaction of α-halo esters.