A convenient synthesis of 4-phenylchalcogeno allenic esters from α-(phenylchalcogeno)acid chlorides

The reaction of ethyl 2-(triphenylphosphoranylidene) acetate or propionate 3a–b with α-chalcogeno ketenes generated in situ by the reaction of α-chalcogeno acid chlorides 1–2 with triethylamine in dichloromethane gives moderate to good yields of 4-phenylchalcogeno allenic esters 4. The corresponding 4-phenylseleno allenic esters 4a–e were obtained in isolated yields of 60 to 93%, while 4-phenylthio allenic esters 4f–j were obtained in isolated yields of 74 to 93%.