Synthesis of enantiopure 2-azabicyclo[3.3.1]nonanes by a radical ring closure

The first synthesis of enantiomerically pure 2-azabicyclo[3.3.1]nonanes by an intramolecular radical reaction of the trichloroacetamido group bearing an (S)-N-1-phenylethyl substituent with the silyl enol ether moiety in comp ounds 7 is described. The procedure allows the two enantiomers of the 2-aza bicyclo[3.3.1]nonane-3,6-dione, 3 and ent-3, to be prepared separately. bet a-Lactam 8 and normorphan 9 are also formed from 7 through an initial radic al translocation process in the cyclization step. (C) 1999 Elsevier Science Ltd. All rights reserved.