One-pot carbanionic synthesis of [P.sup.1],[P.sup.2]-diglycosyl, [P.sup.1],[P.sup.1],[P.sup.2]-triglycosyl, and [P.sup.1],[P.sup.1],[P.sup.2],[P.sup.2]-tetraribosyl methylenediphosphonates

Novel lithiated carbanions derived from ethyl glycosyl- and diglycosyl methylphosphonates are used in a direct synthesis of [P.sup.1],[P.sup.2]-diglycosyl, [P.sup.1],[P.sup.1],[P.sup.2]-triglycosyl, and [P.sup.1],[P.sup.1],[P.sup.2],[P.sup.2]-tetraribosyl methylenediphosphonates involving a one-pot methylidenediphosphonylation of sugars. This new and direct access to di-, tri- or tetraglycosyl methylenediphosphonates can be used in the preparation of compounds of biological interest, if chemoselective hydrolysis of the ethyl ester in the final products is improved.