Selective synthesis of spiro[4,5]trienyl acetates via an intramolecular electrophilic ipso-lodocyclization process

A general and efficient intramolecular electrophilic ipso-iodocyclization of para-unactivated arylalkynes has been developed for the synthesis of spiro[4,5]trienyl acetates. In the presence of NIS (N-iodosuccimide) and HOAc, para-unactivated arylalkynes, including N-arylpropiolamides and phenyl 3-phenylpropiolate, underwent the intramolecular electrophilic ipso-iodocyclization smoothly in moderate to good yields.