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Methyl 3-O-(β-d-mannopyranosyl)-α-d-mannopyranoside was synthesized by the reaction of 3,4,6-tri-O-benzyl-2-O-benzylsulfonyl-1-O-tresyl-d-mannopyranose with methyl 2,4,6-tri-O-benzyl- and 2,4,6-tri-O-(p-bromobenzyl)-α-d-mannopyranoside, followed by deprotection. The corresponding 1-O-(β-tolylsulfonyl)derivative gave better yield and stereoselectivity in the reaction with methanol, but was not sufficiently reactive to couple with a hindered secondary alcohol. The 2-O-benzylsulfonyl group is comparable in β-directing effect to 2-O-methylsulfonyl group, but its stereoselectivity is dependent on the structure of the reactant alcohol. It can be selectively removed by the reaction with sodium amide in N,N-dimethylformamide.

Carbohydrates U 0500Microwave Irradiation for Accelerating the Synthesis of Thioglycosides. -A simple and efficient procedure for the synthesis of thioglycosides of type (III), (V),, (IX), and (XI) is described. The results, compared with those obtained for conducting the reactions without microwaves, show similar yields in shorter reaction times. -(EL ASHRY*, E. S. H.; AWAD, L. F.; ABDEL HAMID, H. M.; ATTA, A. I.; Synth.

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Coupling of dimedone with the diazonium salt of 4‐aminoantipyrine afforded 2,3‐dimethyl‐4‐[2‐(5,5‐dimethyl‐ 2,6‐dioxocyclohex‐2‐ylidend)‐hydrazino]‐5‐oxo‐1‐phenylpyrazoline (3). Reaction of 3 with excess phenylhydrazine gave the mixed trishydrazone derivative 4. Treatment of 3 with hydroxylamine produced the bisoxime 5 which upon dehydrative cyclization with acetic anhydride gave the corrsponding tetrahydrobenzo[d][1,2,3]triazole derivative 7. A one‐pot synthesis of 7 was done by reacting 3 with hydroxylamine hydrochloride in pyridine, followed by heatment with acetic anhydride.