Synthesis and structure of 6-amino-2,3,6-trideoxy-D-erythro-hexono-1,6-lactam and 6-amino-3,6-dideoxy-D-xylo-hexono-1,6-lactam

Solid-state conformations of 6-amino-2,3,6-trideoxy-D-erythro-hexono-1,6-la ctam (3a) and 6-amino-3,6-dideoxy-D-xylo-hexono-1,6-lactam (7a) were determ ined using X-ray diffraction. Conformations of the compounds 3a, 7a, and th eir per-O-acetyl derivatives 4,5-di-O-acetyl-6-amino-2,3,6-trideoxy-D-eryth ro-hexono-1,6-lactam (3b) and 2,4,5-tri-O-acetyl-6-amino-3,6-dideoxy-D-xylo -hexono-1,6-lactam (7b) in solutions were deduced from the analysis of NMR spectra using a modified Karplus equation and compared with the results of circular dichroism measurement of lactams 3a and 7a. Conformation C-4(1,N) was revealed for solid lactams 3a and 7a and for lactams 7a and 7b in solut ion, while lactams 3a and 3b in solution exist in the similar to 1:1 equili brium of the conformers C-4(1,N) and C-1,N(4). (C) 2000 Elsevier Science Lt d. All rights reserved.