Open AccessMethyl 2‐acetamido‐2‐deoxy‐β‐ d ‐glucopyranoside dihydrate and methyl 2‐formamido‐2‐deoxy‐β‐ d ‐glucopyranoside
Author(s) -
Hu Xiaosong,
Zhang Wenhui,
Oliver Allen G.,
Serianni Anthony S.
Publication year - 2011
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
eISSN - 1600-5759
pISSN - 0108-2701
DOI - 10.1107/s0108270111009061
Subject(s) - chemistry , ring (chemistry) , amide , stereochemistry , cyclohexane conformation , crystallography , hydrogen bond , solvent , crystal structure , molecule , biochemistry , organic chemistry
Methyl 2‐acetamido‐2‐deoxy‐β‐ d ‐glucopyranoside (β‐GlcNAcOCH 3 ), (I), crystallizes from water as a dihydrate, C 9 H 17 NO 6 ·H 2 O, containing two independent molecules [denoted (I A ) and (I B )] in the asymmetric unit, whereas the crystal structure of methyl 2‐formamido‐2‐deoxy‐β‐ d ‐glucopyranoside (β‐GlcNFmOCH 3 ), (II), C 8 H 15 NO 6 , also obtained from water, is devoid of solvent water molecules. The two molecules of (I) assume distorted 4 C 1 chair conformations. Values of ϕ for (I A ) and (I B ) indicate ring distortions towards B C2,C5 and C3,O5 B , respectively. By comparison, (II) shows considerably more ring distortion than molecules (I A ) and (I B ), despite the less bulky N ‐acyl side chain. Distortion towards B C2,C5 was observed for (II), similar to the findings for (I A ). The amide bond conformation in each of (I A ), (I B ) and (II) is trans , and the conformation about the C—N bond is anti (C—H is approximately anti to N—H), although the conformation about the latter bond within this group varies by ∼16°. The conformation of the exocyclic hydroxymethyl group was found to be gt in each of (I A ), (I B ) and (II). Comparison of the X‐ray structures of (I) and (II) with those of other GlcNAc mono‐ and disaccharides shows that GlcNAc aldohexopyranosyl rings can be distorted over a wide range of geometries in the solid state.