Structures and Stereochemical Assignments of Some Novel Chiral Synthons Derived from the Biotransformation of 2,3- Dihydrobenzofuran and Benzofuran by Pseudomonas putida

Article abstract of DOI:10.1016/S0957-4166(00)80242-6

Metabolism of 2,3-dihydrobenzofuran using intact cells of Pseudomonas putida UV4 gave mainly (3S)-3-hydroxy-2,3-dihydrobenzofuran which was in turn oxidized to an unstable intermediate, (3S,4R,5S)-3,4,5-trihydroxy-2,3,4,5-tetrahydrobenzofuran.Spontaneous dehydration of this cis,cis-triol occurred in the carbocyclic ring to give (3S)-3,5-dihydroxy 2,3-dihydrobenzofuran and in the heterocyclic ring to yield (4R,5S)-cis-4,5-dihydroxy-4,5-dihydrobenzofuran.Bacterial metabolism of benzofuran was found to occur in the carbocyclic ring to form (6S,7S)-cis-6,7-dihydroxy-6,7-dihydrobenzofuran and its dehydration product, 6-hydroxybenzofuran.Dioxygenase-catalysed cis-dihydrodiol formation in the heterocyclic ring of benzofuran (to give cis-2,3-dihydroxy-2,3-dihydrobenzofuran as a transient intermediate) is proposed to account for the appearance of (1R)-1,2-dihydroxy-1-(2'-hydroxyphenyl)ethane as a major metabolite of benzofuran. cis-4,5-Dihydroxy-4,5-dihydrobenzofuran and cis-6,7-dihydroxy-6,7-dihydrobenzofuran are potentially valuable chiral synthons which can be added to the small pool of bicyclic cis-dihydrodiol metabolites currently available for synthesis.