Reactions between 2-chloromethyl-3-trimethylsilyl-1-propene 1 and N-ac
yliminium ions, which were generated in situ from alpha-methoxy or alp
ha-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 phar
macologically interesting compounds.