TRANS-ANNULAR CYCLIZATION REACTIONS OF PENTACYCLO[6.2.1.02,7.04,10.05,9]UNDECANE-3,6-DIONES - FORMATION OF AZA-BIRDCAGE AND OXA-BIRDCAGE COMPOUNDS

Methoxyamine reacts with cage diketone 1 to afford in excellent yield a mixture of two stereoisomeric di-O-methyloximes 2a and 2b, methylation of which gives quantitatively dimethoxy aza-birdcage amine 3. Further reaction with lithium dimethylcuprate results in displacement of one of the methoxy groups in 3 with a methyl group to give yet another aza-bird compound 6, and its reduction with sodium in liquid ammonia affords cage diamine 5. NMR data of 3 and 6 suggest that both exist as isomeric pairs differing by stereoisomerism at their apical nitrogen atoms, and the hypothesis is supported by isolation of a pair of stereoisomeric p-nitrobenzoates 11 and 12, prepared by reacting 6 with p-nitrobenzoyl chloride. Whereas the diketone 1 reacts with hydroxylamine and tert-bu-tylamine to give bis(hydroxylamine) 14 and a mono-tert-butylimine 15, the tetrachloro cage diketone 16 exhibits only the transannular reactions with nucleophiles. Thus, the oxa-birdcage compounds 17-19 are obtained in near quantitative yields by treating 16 with water, ethanol, and hydroxylamine, respectively. © 1979, American Chemical Society. All rights reserved.