Note

lyslyc2,3X

s R

d Str

Luck

5; accine 8

ra-O-alactnform

2005 Elsevier Ltd. All rights reserved.

years, C-glycosides have gained considerable interestbecause of their signicance as chiral synthons for natural

As a part of our program on the synthesis of C-gly-cosides, 5,6,7,9-tetra-O-acetyl-4,8-anhydro-1,3-dideoxy-

anhydride, and anhydrous sodium acetate at reux.Compounds 1 and 2 were initially characterized by1H and 13C NMR spectroscopy. From the 1H NMR

0008-6215/$ - see front matter 2005 Elsevier Ltd. All rights reserved.

qCDRI Communication No. 6807.* Corresponding author. E-mail: akmisra69@redimail.com

Carbohydrate

Carbohydrate Research 34products syntheses. In addition, C-glycosides are resis-tant to hydrolytic enzymes and as such have been ofinterest as pharmaceutical agents.16 Therefore, C-glyco-sides have been of interest to scientists working in theareas of carbohydrate, enzymatic, and metabolic chem-istry as well as in organic synthesis.711 Because bio-logical activity and enzymatic recognition are closelyrelated to molecular structure, structural comparisonsof C-glycosides with their O-glycoside analogs couldbe useful in designing novel carbohydrate derived thera-peutics. It is important to evaluate whether replacing theglycosidic oxygen with a methylene group (which eradi-cates the exo- as well as endo-anomeric eect and thecapability of hydrogen bonding with the glycosidic oxy-

DD-glycero-LL-gluco-nonulose (1, Fig. 1), a C-glycosideanalog of 1,2,3,4,6-penta-O-acetyl-b-DD-galactopyranose(2) has been prepared following the elegant syntheticmethodology reported by Lubineau and co-workers.13

Although its structure was been established by NMRspectroscopy, it was desirable to further ensure the ste-reochemical integrity at C-1. For this purpose, weundertook an X-ray crystallography study of 1 and 2.This comparative study allowed us to determine dier-ences in the conformation of 1 and 2 in the solid state.Following an earlier report,13 compound 1 was pre-

pared by the reaction of DD-galactose with pentane-2,4-dione in the presence sodium bicarbonate in water.Using another literature procedure,14 compound 2 wasprepared by heating a mixture of DD-galactose, aceticKeywords: C-Glycoside; O-Glycoside; Conformation; X-ray crystallography; Glycosyl acetate

C-Glycosides are close analogs of oligosaccharideswhose intersaccharide oxygen bridges (glycosidic bonds)have been replaced by a methylene moiety. In recent

gen) modies the conformational properties of the mole-cule, resulting in enhanced or impaired biologicalactivity.

12Comparative structural ana4,8-anhydro-1,3-dideoxy-DD-g

1-O-acetylated analog, 1,galactopyranose using

Rishi Kumar, Pallavi Tiwari, Praka

Medicinal and Process Chemistry Division and Molecular an

Chattar Manzil Palace,

Received 6 June 200Available onl

AbstractComparative X-ray diraction analysis of 5,6,7,9-tetand a structurally related analog, 1,2,3,4,6-penta-O-acetyl-b-DD-gthe unit cell and the pyranose rings in both exist in the 4C1 codoi:10.1016/j.carres.2005.07.009is of 5,6,7,9-tetra-O-acetyl-ero-LL-gluco-nonulose and its,4,6-penta-O-acetyl-b-DD--ray crystallographyI

. Maulik and Anup Kumar Misra*

uctural Biology Division, Central Drug Research Institute,

now 226001, UP, India

epted 15 July 2005August 2005

acetyl-4,8-anhydro-1,3-dideoxy-DD-glycero-LL-gluco-nonulose (1)opyranose (2), are reported. Both crystals have one molecule ination.

RESEARCH0 (2005) 23352339