Glycosyl Bunte Salts: A Class of Intermediates for Sugar Chemistry.
S-Glycosyl thiosulfates have been discovered as a new class of synthetic intermediates in sugar chemistry, named "glycosyl Bunte salts" after 19th-century German chemist, Hans Bunte. The synthesis was achieved by direct condensation of unprotected sugars and sodium thiosulfate using a formamidine-type dehydrating agent in water-acetonitrile mixed solvent. The application of glycosyl Bunte salts is demonstrated with transformation reactions into other glycosyl compounds such as a 1-thio sugar, a glycosyl disulfide, a 1,6-anhydro sugar, and an O-glycoside.
Promoting Effect of Crystal Water Leading to Catalyst-Free Synthesis of Heteroaryl Thioether from Heteroaryl Chloride, Sodium Thiosulfate Pentahydrate, and Alcohol.
It is observed the crystal water in sodium thiosulfate pentahydrate (Na2S2O3•5H2O) can promote its multi-component reaction with heteroaryl chlorides and alcohols, providing a facile, green and specific synthesis of unsymmetrical heteroaryl thioethers via one-step formation of two C-S bonds under catalyst-, additive-, and solvent-free conditions. Mechanistic studies suggest that the crystal water in Na2S2O3•5H2O is crucial in generating the key thiol intermediates and byproduct NaHSO4, which then catalyzes the dehydrative substitution of alcohols with thiols to afford thioethers.
The Transformations of Dimeric Tri-O-acetyl-2-deoxy-2-nitroso-α-D-hexopyranosyl Chlorides in Dimethylformamide
The dimeric nitrosyl chloride adducts of tri-O-acetyl-1,5-anhydro-2-deoxy-D-arabino-hex-1- and D-lyxo-hex-1- enitols (glycals) dissociate in dimethylformamide to the monomeric forms which rapidly isomerize to the corresponding tri-O-acetyl-2-oximino-α-D-hexopyranosyl chlorides. Evidence is provided for the dehydrochlorination of these latter compounds to highly reactive tri-O-acetyl-1,5-anhydro-2-deoxy-2-nitroso-D-hex-1-enitols.