Synthesis of enantiopure 1-azabicyclo[3.2.2]nonanes via stereoselective capture of chiral carbocations.
[reaction: see text] A new class of doubly functionalized and enantiomerically pure 1-azabicyclo[3.2.2]nonanes derived from quincorine and quincoridine is described. 2,5-Disubstituted quinuclidines with a C9-mesyloxy group were easily transformed into the corresponding halides upon treatment with lithium salts. Subsequent silver salt-mediated ring expansion stereoselectively furnished the title azabicyclics. Chiral carbocations which are configurationally stable and nonplanar are postulated to account for the striking stereoselectivity of the capture of external nucleophile. 5-Ethynyl-2-iodomethylquinuclidines afford the alpha-benzoyloxy amines rather than alpha-methoxy amines, even in MeOH.
Röper
S
S
Department of Organic Chemistry, University of Hannover, Schneiderberg Germany.
Frackenpohl
J
J
Schrake
O
O
Wartchow
R
R
Hoffmann
H M
HM
D000588:Amines / Q000138:chemical synthesis / Q000737:chemistry*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000138:chemical synthesis / Q000737:chemistry*; D018680:Cholinergic Antagonists / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011812:Quinuclidines / Q000737:chemistry; D013237:Stereoisomerism; D014961:X-Ray Diffraction
D000588:Amines; D019086:Bridged Bicyclo Compounds, Heterocyclic; D018680:Cholinergic Antagonists; D011812:Quinuclidines