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

Abstract

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 compounds 7 is described. The procedure allows the two enantiomers of the 2-azabicyclo[3.3.1]nonane-3,6-dione, 3 and ent- 3, to be prepared separately. β-Lactam 8 and normorphan 9 are also formed from 7 through an initial radical translocation process in the cyclization step.