Novel tocopheryl compounds XX. 1,3,8-Trioxaphenanthrenes derived from γ-tocopherol

Condensation of γ-tocopherol with aldehydes provides 2,4-disubstituted 1,3,8-trioxaphenanthrenes in a simple one-pot reaction. The reaction proceeded under acid catalysis according to a two-step alkylation-acetalisation mechanism in yields between 58 and 81%. The title compounds are precursors for the thermal generation of ortho-quinone methides, which can be in situ reduced to give antioxidants of the 5a-substituted α-tocopherol-type. The products were analytically characterized by NMR and HRMS.