Synthesis and Conformation of 6-Amino-3,6-dideoxyhexono-1,6-lactams

Abstract

Three isomeric 6-amino-3,6-dideoxyhexono-1,6-lactams of D-ribo (1a), L-lyxo (2a) and L-arabino (3a) configuration were synthesized via the corresponding 6-azido-3,6-dideoxyhexoses starting from 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose. Conformation of lactams 1a, 2a and 3a and their tri-O-acetyl derivatives 1b, 2b and 3b was studied using NMR spectroscopy. CD spectra of the lactams 1a-3a, together with the D-xylo diastereoisomer 4a, were measured and interpreted according to semiempirical rules. NMR and CD measurements confirmed the chair conformation with an equatorial substituent on C-2 as prevailing for the all measured lactams.