Formation of enantiopure beta-amino alcohols with a 3-oxa-2,7-diazabicyclo[3.3.0]octane framework

N-Allylamino alcohols 11a-g were prepared from enantiopure (IS, 2S)-2-amino -1-phenylpropane-1,3-diol (8) by various reaction pathways. Selective Swern oxidation of the primary alcohol group of compounds 11 followed by treatme nt of the resulting aldehyde with N-alkylhydroxylamines afforded the corres ponding nitrones that underwent an intramolecular 1,3-dipolar cycloaddition to give the bicyclic compounds 12 and 13. 12c and 13c (R-3 = allyl) were d eallylated providing compounds 12i and 13i, which could be methylated subse quently yielding 12k and 13k, respectively. X-ray analyses of 13a,c and 12g were performed indicating different conformations of 13a and c on the one hand and of 12g on the other hand. Conclusions concerning the conformation of the other compounds 12 and 13 were drawn from their H-1 NMR data. Compou nds 12 and 13 act as chiral ligands in the enantioselective addition of die thylzinc to benzaldehyde, however, the enantiomeric excess of the 1-phenylp ropane-1-ol is usually low, the best result (79% ee) was achieved with comp ound 12c. (C) 1999 Elsevier Science Ltd. All rights reserved.