A New Route to N‐Aryl 2‐Alkenamides, N‐Allyl N‐Aryl 2‐Alkenamides, and N‐Aryl α,β‐Unsaturated γ‐Lactams from N‐Aryl 3‐(Phenylsulfonyl)propanamides

A series of N ‐aryl 2‐alkenamides were produced efficiently by treating N ‐aryl 3‐(phenylsulfonyl)‐propanamides with potassium tert ‐butoxide in THF at 0°C. With out isolation, it was further treated with an additional equivalent 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 metathesis reaction, these N ‐allyl N ‐aryl 2‐alkenamides were respectively converted into corresponding N ‐aryl α,β‐unsaturated γ‐lactams in moderate yields.