A straight synthesis of 2–(α-substituted N-tosylaminomethyl)-2,5-dihydrofurans by the reaction of N-sulfonylimines with arsonium 4-hydroxyl- cis -2-butenylides

On treatment of N-tosylimines (1) and 4-hydeoxyl- cis-butenyl arsonium salt (5) with KOH in acetonitrile at room temperature, 2–(α-substituted N-tosylaminomethyl)-2, 5-dihydrofurans (4) were obtained in moderate yields. The arsonium salt (5) acts formally as an equivalent of 2,5-dihydrofuran synon. A plausible mechanism was proposed for this new 5-membered cyclization reaction.