Synthesis of an Antioxidant Having a Dibenz[b,f]oxepine Skeleton

A -t-Dibenz[b,floxepine derivative (1) isolated from a yeast as an antioxidant was synthesized via 17 reaction steps starling from methyl gallate.However, the physicochemical data of the synthetic compound (1) were different from the previously reported values.Moreover, the antioxidative activity of the synthetic 1 was slightly more active than that of the natural product.Dibenz[b,floxepines and their analogues, dibenzo[b,flthiepines, have been popular synthetic targets for drugs such as antidepressant' and antiinflammatory agents2 In contrast, except cularine alkaloids' few are naturally occurring dibenz[b,floxepines; they were mainly originated from medicinal plants.'To our knowledge, little work has been done on total syntheses of natural simple dibenzoxepines.'An antioxidant, l-hydroxy-3,4-methylendioxy-ll-methoxydibenz[b,floxepe (I), was isolated from Saccharomyces cerevi~siae.~It was slightly less active than a-tocopherol, a well-known naturalantioxidant.This compound has generated our interest, due to its structural features in several functional groups and highly oxygenated C ring, and other biological activities would be also expected from the structure of its dihenz[b,floxepine skeleton.As part of our continuing work on antioxidants, we report herein on a total synthesis of 1 and its antioxidative activity.