Synthesis of Enantiopure 1-Azabicyclo[3.2.2]nonanes via Stereoselective Capture of Chiral Carbocations
摘要:
[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-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.
Novel Bridged Bicyclic α-Amino Acid Esters and Key Derivatives from Quincorine and Quincoridine
摘要:
Oxidation of Quincorine (QCl) and Quincoridine (QCD) has been investigated, giving bicyclic a-amino acids and dicarboxylic acid derivatives, which are epimerically and also enantiomerically pure. Acidic Cr(VI)-mediated oxidation (Jones oxidation) has been optimized with respect to reaction conduct and work up (addition of ethylenediamine).
Novel Bridged Bicyclic α-Amino Acid Esters and Key Derivatives from Quincorine and Quincoridine
作者:Olaf Schrake、Volker S. Rahn、Jens Frackenpohl、Wilfried M. Braje、H. Martin R. Hoffmann
DOI:10.1021/ol990981o
日期:1999.11.1
Oxidation of Quincorine (QCl) and Quincoridine (QCD) has been investigated, giving bicyclic a-amino acids and dicarboxylic acid derivatives, which are epimerically and also enantiomerically pure. Acidic Cr(VI)-mediated oxidation (Jones oxidation) has been optimized with respect to reaction conduct and work up (addition of ethylenediamine).
Synthesis of Enantiopure 1-Azabicyclo[3.2.2]nonanes via Stereoselective Capture of Chiral Carbocations
作者:Stefanie Röper、Jens Frackenpohl、Olaf Schrake、Rudolf Wartchow、H. M. R. Hoffmann
DOI:10.1021/ol0057378
日期:2000.6.1
[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-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.