Various kinds of nonbranched and methyl-branched 6-deoxyhex-5-enopyranoside derivatives were prepared from 6-bromo-6-deoxy or 6-O-p-tolylsulfonylhexopyranoside in a one-pot procedure by a successive treatment with iodide anion and 1,8-diazabicyclo[5.4.0]undec-7-ene in dimethyl sulfoxide. The scope and limitations of this reaction have become apparent by observing the reactions of 18 substrates. The yields of altropyranoside and 2-deoxyribo-hexopyranoside derivatives were high, except for the 2,3-anhydropyranoside derivative. Methyl-branched 6-deoxyhex-5-enopyranoside derivatives were also obtained in practical yields.
Methyl β-d-glucopyranoside reacted with a 4-molar excess of the Mitsunobu reagents (triphenylphosphine–diethyl azodicarboxylate–benzoic acid) under Weinges et al. [Carbohydr. Res., 164 (1987) 453–458] conditions to furnish four differently benzoylated methyl β-d-allopyranosides in a very good overall yield. The same reaction applied to methyl α-d-glucopyranoside yielded allosides in a low yield and