Synthesis of (2RS, 4′R, 8′R) -α-Tocopherol by Ultrasonic Method

Abstract

Ethyl [1-¹³C] -bromoacetate was synthesized by the bromination of [1-¹³C] -acetic acid and subsequent EtOH treatment.
Reaction of ethyl [1-¹³C] -bromoacetate and phytone in the presence of zinc under ultrasonic conditions gave ethyl [1-¹³C] -3-hydroxy-3, 7, 11, 15-tetramethylhexadecanoate (5) in 57 % yield.
Compound (5) was converted quantitatively to the 1, 3-diol whose condensation with trimethyl hydroquinone gave (2 RS, 4′ R, 8′ R) -α-tocopherol. (2 RS, 4′R, 8′ R) -α- [4-¹³C] -tocopheryl acetate was obtained by treating the tocopherol with acetic anhydride and pyridine.