Lyxose dithioacetal

Zinner and coworkers studied88 the possibility of formation of 1-thioaldo-furanosides from other sugar dithioacetals, and noted that, both with D-mannose dithioacetals and D-xylose dithioacetals, only the free sugar was formed no thiofuranosides were obtained. With D-lyxose dithioacetals, both the free sugar and the 1-thiofuranoside were formed the latter, detected in only small amounts (on a paper chromatogram), was not isolated. 

Deoxy lyxose 1-Deoxy lyxitol Lyxose dithioacetal Ribose Derivatives... 

The reaction of p-D-ribopyranose tetraacetate (63) with methanethiol and zinc chloride gave 32), after deacetylation, methyl 1-thio-p-D-ribo-pyranoside (64), methyl 1,5-dithio-p-D-ribopyranoside (72, R=H), 4-S-methyl-4-thio-L-lyxose dimethyl dithioacetal (77, R=H), and a small... 

SCHEME 2. Richardson s unsuccessful attempted oxidative degradation of a D-lyxose diethylsulfonyl dithioacetal possessing a fused acetal (1959). 

Conversion of tetra-0-acetyl-/3-D-ribopyranose into methyl 1-thio-/3-D-ribopyranoside, by the action of methanethiol and zinc chloride, with subsequent deacetylation, is accompanied by the formation of substantial proportions of methyl l,5-dithio-j8-D-ribopyranoside (55) and 4-S-methyl-4-thio-L-lyxose dimethyl dithioacetal (53), plus a trace of 5-S-methyl-5-thio-D-ribose dimethyl dithioacetal (56). Although similar treatment of tetra-O-acetyl-jS-D-ribofuranose for a short time produced the expected methyl 1-thio-jS-D-... 

Walker et al. have described by tliis method a seven-step synthesis of 4-thio-2-deox-y-i3-eri f/7ro-pentosc (37) from 2-dcoxy-D-erir/ira-pentosc via dithioacetals 35 and 36, involving inversion at C-4 by Mitsunobu reaction and final cyclization of the dithioacetal, accompanied by further inversion at C-4. Secrist et al.- have synthesized 39 from the ribose derivative 38 using the same method. Similarly, Imbach et al. have prepared 1,4-dithio-D-ribofuranosides 39 from L-lyxose and from D-ribose,and 1,4-dithio-L-lyxofuranosides 40 from D-ribose. Mackenzie... 

Acetals and Dithioacetals of 2-S-Ethyl-2-thio-D-xylose(lyxose), M. L. Wolfrom and Walter von Bebenburg,y. Amer. Chem. Soc., 82, 2817—2819 (1960). 

Tetra-Ac 2,3,4,5-Tetra-O-acetyl-D-lyxose dibenzyl dithioacetal C27H32O8S2 548.677 Needles (MeOH). Mp 103.5°. [a] +198 (c, 1.8 in MeOH). 

Anhydro-l,6-di-0-tosyl-L-iditol, A-654 2,5 Anhydro-3,6-di-0-tosyl-L-idose dimethyl dithioacetal, A-657 2,5 Anhydro-3,4-di-0-tosyl-D-lyxose dimethyl acetal, A-665 2,5 Anhydro-3,4-di-0-tosyl-L-lyxose dimethyl acetal, A-665... 

Further examples of rearrangements involving cyclic sulphonium ions have been reported. Thus 2,3,5-tri-0-methyl-4-0-toluene-/>-sulphonyl-D-ribose diethyl dithioacetal (184) and dibenzyl dithioacetal (185) gave 4- S -ethyl-2,3,5-tri-0-methyl-4-thio-L-lyxose (186) and benzyl 2,3,5-tri-0-methyl-l,4-dithio-a-L-lyxo-furanoside (187) (Scheme 46) when heated either in aqueous pyridine or with sodium iodide in acetone similar rearrangements to the 4-thiofuranosides were observed with 2,3,5-tri-0-methyl-4-0-toluene-p-sulphonyl-D-xylose and -lyxose... 

The diastereoisomeric 1-phenylethyl dithioacetals of arabinose, lyxose, fucose, rhamnose, galactose, glucose and mannose have been prepared and separated conventionally. 

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