Novel synthesis of lactam from alkyne having amide in a tether using Fischer chromium carbene complex

A novel lactam synthesis from alkyne having amide in a tether was developed. The reaction proceeds via a vinylketene complex generated from alkyne and Fischer chromium carbene complex, and the lactam ring was formed from carbon monoxide, alkyne carbon and nitrogen of tosylamide. The four-, five-, six-, and seven-membered lactams having a substituent at the alpha-position were obtained in good yields.