Easy route to labeled and unlabeled R,R,R-γ-tocopherol by aryl demethylation of α-homologues

The interest in vitamin E research is increasingly focusing on the peculiar properties of the less investigated tocopherols and their metabolites, such as γ-tocopherol, which have been revealed as very important for human health. Metabolic studies of γ-tocopherol have been constricted by its high cost and the poor availability of stable isotope-labeled forms. An efficient, inexpensive and simple route is described for the preparation of labeled and unlabeled R,R,R-γ-tocopherol, starting from R,R,R-α-tocopherol, through simple thermal decarboxylation of γ-tocopherol-5-carboxylic acid.