Highly regioselective hydroiodination of terminal alkynes and silylalkynes with iodine and phosphorus reagents leading to internal iodoalkenes

Markovnikov-type hydroiodination of terminal alkynes with iodine and Ph2P(O)H took place selectively to afford the corresponding internal iodoalkenes in good yields. Combination of (PhO)2P(O)H and Ph2P(O)OH instead of Ph2P(O)H also provided internal iodoalkenes in excellent yields. This hydroiodination is advantageous in terms of mild conditions, convenient operation, and tolerance to various functional groups. In addition, direct synthesis of internal iodoalkenes from silylalkynes was also achieved by using a mixed system of iodine and phosphorus reagents.