Hetero-Diels–Alder synthesis of the spiroketal fragment of reveromycin A

The asymmetric synthesis of the 6,6-spiroketal fragment 15 of the epidermal growth factor inhibitor reveromycin A (1) is described. A hetero-Diels–Alder reaction was utilized to construct the 6,6-spiroketal 14 and subsequent stereoselective hydroboration provided reveromycin A spiroketal 15.