Abstract

The reaction of (trimethylsilyl)diazomethane with methyl (diethoxyphosphonyl)dithioformate (2), after elimination of N2 at –35°C, yields the 4,5-bis(trimethylsilyl)-1,3-dithiolane-2-phosphonate (8). This product is the result of the dimerization of the intermediate silylated thiocarbonyl ylide (4b) to give the cyclic sulfonium ylide (7), followed by the elimination of a disubstituted carbene. Trapping of the intermediate (4b) with maleimide (9), maleic anhydride (10), thiobenzophenone (11), and the phosphonylated dithioformate (2) yields the corresponding [2+3] cycloadducts (12), (13), (14b), and (18), respectively. The crystal structures of 13 and 14b have been established by X-Ray crystallography.