A new route to N-aryl 2-alkenamides, N-allyl N-aryl 2-alkenamides, and N-aryl alpha,beta-unsaturated gamma-lactams from N-aryl 3-(phenylsulfonyl)propanamides

A series of N-aryl 2-alkenamides were produced efficiently by treating N-ar yl 3-(phenylsulfonyl)propanamides with potassium tert-butoxide in THF at 0 degrees C. Without isolation, it was further treated with an additional equ ivalent of potassium tert-butoxide and allyl bromide to give N-allyl N-aryl 2-alkenamides in one pot in good yields. Followed by a ring-closing metath esis reaction, these N-allyl N-aryl 2-alkenamides were respectively convert ed into corresponding N-aryl alpha,beta -unsaturated gamma -lactams in mode rate yields.