REGIO AND STEREOSELECTIVE CONVERSION OF DELTA(4)-URONIC ACIDS TO L-IDOPYRANOSIDURONIC AND D-GLUCOPYRANOSIDURONIC ACIDS

Synthesis of L-ido- and D-glucopyranosiduronic acids was performed sta rting from protected Delta(4)-uronic acids 3a-f. Bromination of the C- 4,5 double bond provided the trans-diaxial bromohydrin derivatives 6a- d, which were converted to the corresponding epoxides 7a-d in high yie lds. Direct reduction of these epoxides using borane-tetrahydrofuran c omplex afforded the o-glucopyranosiduronic acids 9b-d, while Lewis aci d rearrangment through the C-4 keto intermediate 10b-d afforded the L- idopyranosiduronic acids 11b-d. (C) 1997, Elsevier Science Ltd.