Methyl esters of N-protected-O- or -S-(4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-enopyranosyl)-L-serine, -L-threonine and -L-cysteine: Synthesis and some transformations

Methyl esters of N-tosyl-O-(4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-eno pyranosyl)-L-serine (5), -L-threonine (6) and N-benzoyl-S-(4,6-di-O-acetyl- 2,3-dideoxy-alpha- D-erythro-hex-2-enopyranosyl)-L-cystein (7) have been sy nthesized by condensation of 3,4,6-tri-O-acetyl-1,5-anhydro-2-deoxy-D-arabi no-hex-1-enitol (1) with respective derivatives of L-serine (2), L-threonin e (3) and L-cysteine (4). cis-Hydroxylalion and epoxydation of 2,3-unsatura ted glycopyranoside 5 afforded O-glycosyl-L-serine derivatives with cr-D-ma nno (8, 9), 2,3-anhydro-alpha-D-manno (10) and 2,3-anhydro-alpha-D-allo (Il )structures, respectively. The structure of compounds as well as conformati on of the sugar residue and configuration at the anomeric centre were estab lished on the basis of the H-1 and C-13 NMR (DQF-COSY, TOCSY, HMBC), TR, MS (FD) spectrometric techniques and polarimetric data.