2,6-Anhydro-2-thio sugars

A hydroxysulfoxide was desulfurized with Ra-Ni in MeOH for 30 minutes.400 Treatment with hydrogen in the presence of catalytic amounts of Ra-Ni in EtOH caused the desulfurization of a 2,6-anhydro-2-thio sugar, the reduction of an N-oxide, and the removal of benzyl and carbomethoxy groups at the... 

A full account of the use of 2,6-anhydro-2-thio sugars for the stereo-controlled synthesis of 2,6-dideoxy-a- and 3-glycosides has appeared, and the method has been applied to the synthesis of erythromycin A and olivomycin A trisac-charide. ... 

Scheme 27. 2,6-Anhydro-2-thio sugars as glycosyl donors for the stereospecific synthesis of 2-deoxy-a- and fl-glycosides.

Scheme 28. Armed-disarmed glycosylation with 2,6-anhydro-2-thio sugars.

Toshima K, Mukaiyama S, Yoshida T, Tamai T, Tatsuta K. Application of efficient glycosylation of 2,6-anhydro-2-thio sugar to the total synthesis of er)Thromycin A. Tetrahedron Lett. 1991 32 6155-6158. 

Toshima K, Mukaiyama S, Nozaki Y, Inokuchi H, Nakata M, Tatsuta K. Novel glycosidation method using 2,6-anhydro-2-thio sugars for stereocontroUed synthesis of 2,6-dideoxy-a-and -p-glycosides. J. Am. Chem. Soc. 1994 116 9042-9051. 

The preparation of a number of anhydro thio sugars is based on this S neighboring-group participation. 

Four-membered anhydro thio sugars have also been prepared by reactions that involve neighboring S groups. The D-mannitol derivative (282) was converted into the tricyclic D-iditol derivative (283) with methanolic... 

A total synthesis of erythromycin A involved use of the thiogly-coside of the anhydro-thio sugar (12) which allowed easy glycosyl-... 

The first synthesis of a thio sugar by epoxide scission to be reported was the preparation of 1,2-0-isopropylidene-6-thio-D-glucose (67, R = H) from 5,6-anhydro-l,2-0-isopropylidene-a-D-glucofuranose (66) by the action of hydrogen sulfide. The product was isolated as the crystalUne... 

Acetylated 6" -deoxy-6 -iodo-maltotriose and 6 -deoxy-6 -iodo-malto-tetraose have been prepared and the iodide has been displaced with the thio group of another 1-thio-sugar. 2,5-Anhydro-D-mannitol has been converted into 3,4-di-0-acetyL-2,5-anhydro-l,6-dideoxy-l,6-diiodo-D-mannitol by standard methods, and 4-deoxy-4-iodo-daimosamine has been prepared as an analogue of daunosamine. 3,6-Dideoxy-6-iodo-1,2- O-isopropyhdene-a-D-glucofuranose has been prepared in high yield by treatment of the corresponding 3-deoxy-5,6-thionocarbonate with methyl iodide. ... 

C-3 in the unsubstituted compound.176,177 However, at the time of these experiments, only C-3 substitution had been observed with 2,3-anhydropentofuranosides, and the results of investigation of this reaction suggest that the amino sugar substituted at C-2 is the major product.184 With thiocyanate ion, substitution also occurs at C-3, leading to the thietane derivative, namely, methyl 3,5-anhydro-3-thio-a-D-xylofuranoside (59) but, as this compound was obtained in only 25% yield, the major pathway may involve 2-substitution, leading to products not characterized.178... 

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