Reactions between 2-chloromethyl-3-trimethylsilyl-1-propene 1 and N-acyliminium ions, which were generated in situ from α-methoxy or α-acetoxy amides 2, give allylic chlorides 3 in good yields and high stereoselectivities. The allylic chlorides 3 were further transformed to bicyclic methylenepyrrolidines 4 which are building blocks for pharmacologically interesting compounds.