Displacement of 'pseudoanomeric' hydroxyl groups by using the diethyl azodicarboxylate-triphenylphosphine system

1 d -(1,2,4/3)-2,3,4-Tri- O -benzyl-5-(trityloxymethyl)-5-cyclohexene-1,2,3,4-tetrol ( 5a ) and its 1 l -(1,3/2,4) isomer ( 5b ) were prepared from d -glucose, and they underwent ready mutual interconversion through an S N 2 procedure employing a benzoic acid-diethyl azodicarboxylate-triphenylphosphine system and subsequent basic hydrolysis. Azido, phthalimido, and even more complex nucleophile groups could similarly also substitute the allylic hydroxyl groups of 5a and 5b by using the same system, with a few different results between 5a and 5b .