Synthesis of enantiopure 1-azabicyclo[3.2.2]nonanes via stereoselective capture of chiral carbocations

[GRAPHICS] A new class of doubly functionalized and enantiomerically pure 1-azabicyclo [3.2.2]nonanes derived from quincorine and quincoridine is described. 2,5-D isubstituted quinuclidines with a C9-mesyloxy group were easily transformed into the corresponding halides upon treatment with lithium salts. Subseque nt silver salt-mediated ring expansion stereoselectively furnished the titl e azabicyclics. Chiral carbocations which are configurationally stable and nonplanar are postulated to account for the striking stereoselectivity of t he capture of external nucleophile. 5-Ethynyl-2-iodomethylquinuclidines aff ord the alpha-benzoyloxy amines rather than alpha-methoxy amines, even in M eOH.