Reaction of methyl trichloroacetate with vinyltrimethylsilane in the presence of metal carbonyls

Reaction of methyl trichloroacetate with vinyltrimethylsilane initiated by metal carbonyls yields, depending on the crbonyl, methyl-2,2,4-trichloro-4trimethyl-silyl butyrate [with Mn2(CO)10 or Re2(CO)10], 2,2-dichloro-4-trimethylsilyl-γ-butyrolactone [with Fe(CO)5 or Mo(CO)6], or a mixture of adduct and lactone [with Cr(CO)6 or W(CO)6]. Prior nucleophilic addition of potassium acetate to metal carbonyls of Fe, Mo, Cr, and W suppresses lactonization and an adduct is formed. In the case of Fe(CO)5, HMPA, DMF, and PPh3 react analogously.