Regiospecific synthesis of a bridgehead-functionalized bicyclo[2.2.2]octenone

Three independent strategies are tested toward the synthesis of the protected 1-aminobicyclo[2.2.2]octene ketodiester 1. One of these three is found to be completely regioselective. It proceeds by Diels–Alder addition of dimethyl acetylenedicarboxylate to the silyl enol ether of 3-benzyloxycarbonyl-2-cyclohexenone, followed by a chemoselective Curtius rearrangement.