Palladium-Catalyzed Desulfurative Carbocyclizations of α-(3-Butenoyl) Ketene Dithioacetals in the Presence of Silanes

A combination of palladium and silane has been well used for the catalytic desulfurative cross‐coupling reactions under neutral conditions. Catalyzed by 10 mol‐% of bis(triphenylphosphine) palladium(II) dichloride in dimethylformamide in the presence of 2 equiv. of triphenylsilane, the carbocyclizations of α‐(3‐butenoyl) ketene dithioacetals took place smoothly leading to 2‐cyclopentenones in high yields. Thus, a new Heck‐type cyclization based on C–S bond cleavage for the synthesis of spiro compounds by using silanes as the desulfurative agents has been established. A combination of palladium and silane has been well used for the catalytic desulfurative carbocyclization of α‐(3‐butenoyl) ketene dithioacetals leading to 2‐cyclopentenones under neutral conditions. Thus, a new Heck‐type cyclization based on C–S bond cleavage for the synthesis of spiro compounds by using silanes as the desulfurative agents has been established.