Synthesis of iminomethano-dibenzo[a,e]cyclooctenes by transannular formation and cleavage of isoxazolidines

Regioselective formation of the 7-azabicyclo4,2,2]decanone (4) was accomplished by reaction of hydroxylamine with the enone (10) and subsequent reduction of the isoxazolidine adduct (11); intramolecular nitrone cycloaddition of (19) gave a 2:1 mixture of the regioisomers (17) and (18) which were reduced to give the bridgehead methylated, -hydroxylated, 3,3,2] and 4,2,2] iminomethano compounds (5) and (6).