1-Thiosugars preparation

Stereocontrolled synthesis of thiosugars from acyclic precursors and preparation of pseudonucleosides with thiosugar moiety 97YGK186. 

S -Alkyl thiocarbamates (Table 4.24) have been synthesized [I] by a procedure (Scheme 4.19) which is closely analogous to that employed for the preparation of S-alkyl thiocarbonates (see Section 4.1), S-Glycosyl dithiocarbamates [2], which are useful precursors for thiosugars, have been prepared by simple nucleophilic displacement of the tosyloxy group by the N,N-diethyldithiocarbamate anion (cf preparation of S-glycosyl dithiocarbonates, 4.1.13). 

Thiosugars can be rapidly synthesized when sulfur-substituted aldehydes are condensed with DHAP under the influence of FDP aldolase.42 The synthesis of these heterocycles is completed by phosphate cleavage, acetylation and reduction of the resultant ketone (Scheme 5.20). Cyclitols, another interesting class of biologically active compounds, have been prepared through the reaction of phosphonate- and nitro-substituted aldehydes with DHAP under the influence of FDP aldolase (Scheme 5.21) 43,436... 

Diaslereomerically pure thiosugar derivative 18 was prepared from intermediate 17 by initial deoxygenation at the 2-position followed by Hanessian phenylthioglycosidation and base-induced carbonate removal137. 

Another series of interesting thiosugars was prepared by Schubert by the action of cysteine on the aldoses. By analogy with the structure assigned by this same author to the reaction product of cysteine with ordinary aldehydes, these new compounds may be formulated as the open chain forms ... 

Along synthetic lines, the preparation of the first thiosugar with the sulfur attached to a non-carbonyl carbon appears to be due to Wrede. " He had obtained di(glucosyl-6) sulfide by treating methyl 6-bromo-/3-D-... 

Sulfoxides and sulfones have been prepared by oxidation of thiosugars but have only found very limited use as carbohydrate mimics. 

Scheme 16 Synthetic preparation of the thiosugar l-deoxy-4-thio-D-arabinolhranose...

Maillard et al. [49] described a synthetic methodology to prepare the thiosugar-diethylene glycol porphyrin derivatives 88 and 89 (Scheme 16). Condensation of 2,3,4,6-tetra-O-acetyl-l-thio- -o-galactopyranose or 2,3,4,6-tetra-O-acetyl-l-thio-a-o-maimopyranose with the 5,10,15-rris(p-bromo-ethoxyethoxyphenyl)-20-phenylporphyrin 87, previously prepared from 43... 

Ethyl 2,3,4-tri-0-acetyl-l-thio- 3-L-rhamnopyranoside has been prepared by way of the diethyldithioacetal, and the cysteamine 5-glucuronide (70) was obtained both by use of a glyuronosyl bromide derivative and by treatment of a 1-thiosugar derivative with 2-bromoethylamine. 5-Benzyl thioglycosides of... 

Thioglycosyl pyridine iV-oxides, e.g. compound 42, have been prepared as latent glycosyl donors from peracetylated 1-thiosugars and 2-bromopyridine-N-oxide. MCPBA oxidation of ethyl 1-thio-p-glycopyranosides gave the corresponding Sj-sulfoxides, for example 43, as the major products. The preferred conformations of the minor Rj-epimers under the influence of the exo-anomeric effect are discussed in Chapter 21. ... 

A review of the work at Novartis on the synthesis of complex compounds on solid supports includes the preparation and use of solid-phase bound thiosugars derived from levoglucosan ... 

For work on insulin-like and insulin-antagonist properties, a range of substituted phenyl and benzyl l-thio-a-D-mannopyranosides were prepared either by alkylation of the 1-thiosugar or by use of glycosylthiourea derivatives. ... 

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