1. Practical synthesis of the 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glucosides of Fmoc-serine and Fmoc-threonine and their benzyl esters
Ivone Carvalho, Shona L Scheuerl, K P Ravindranathan Kartha, Robert A Field Carbohydr Res. 2003 May 1;338(10):1039-43. doi: 10.1016/s0008-6215(03)00071-5.
Mercuric bromide-promoted glycosylation of Fmoc-Ser-OBn and Fmoc-Thr-OBn with 2-acetamido-2-deoxy-3,4,6-tri-O-acetyl-alpha-D-glucopyranosyl chloride in refluxing 1,2-dichloroethane gave the corresponding beta-glycosides in good yields (64 and 62%, respectively). Direct coupling of the commercially available Fmoc-Ser-OH and Fmoc-Thr-OH carboxylic acids under similar conditions gave the corresponding beta-glycosides, possessing free carboxyl groups, in moderate yields (50 and 40%, respectively).
2. N-(2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-alpha-D-galactopyranosyloxy)succinimide
O Renaudet, P Dumy, C Philouze, M T Averbuch-Pouchot Acta Crystallogr C. 2001 May;57(Pt 5):649-50. doi: 10.1107/s0108270101003377. Epub 2001 May 15.
The crystal structure of the title compound, C18H24N2O11, a GalNAc mimic containing an alpha-glycosyloxysuccinimide linkage, has been determined. The pyranose ring geometry is an almost perfect (4)C(1) chair. The torsion angle of the exocyclic hydroxymethyl group is shown to be gauche-trans with respect to O1 and C4, respectively.
3. The synthesis of 2-acetamido-2-deoxy-6-O-beta-D-mannopyranosyl-D-glucose
M A Shaban, I E Ary, D A Jeanloz, R W Jeanloz Carbohydr Res. 1975 Dec;45:105-14. doi: 10.1016/s0008-6215(00)85870-x.
4,6-Di-O-acetyl-2,3-O-carbonyl-alpha-D-mannopyranosyl bromide was condensed with benzyl 2-acetamido-3,4-di-O-acetyl-2-deoxy-alpha-D-glucopyranoside in the presence of silver carbonate to give crystalline benzyl 2-acetamido-3,4-di-O-acetyl-2-deoxy-6-O-(4,6-di-O-acetyl-2,3-O-carbonyl-beta-D-mannopyranosyl)-alpha-D-glucopyranoside in 32% yield. Removal of the protective O-acetyl and cyclic carbonate groups gave the crystalline benzyl alpha-glycoside of the disaccharide, which was catalytically hydrogenolyzed to yield the crystalline, title compound. Proof of the anomeric configuration of the interglycosidic linkage was obtained by comparison of the physical, spectral, and chromatographic properties of the disaccharide and its derivatives with those of the previously prepared alpha-D-linked analog.