Synthesis of [¹³C₃]-B6 vitamers labelled at three consecutive positions starting from [¹³C₃]-propionic acid

[¹³C₃]-labelled vitamers (PN, PL and PM) of the B6 group were prepared starting from [¹³C₃]-propionic acid. [¹³C₃]-PN was synthesized in ten linear steps with an overall yield of 17%. Hereby, higher alkyl homologues of involved esters showed a positive impact on the reaction outcome of the intermediates in the chosen synthetic route. Oxidation of [¹³C₃]-PN to [¹³C₃]-PL was undertaken using potassium permanganate and methylamine followed by acid hydrolysis of the imine derivative. [¹³C₃]-PM could be prepared from the oxime derivative of [¹³C₃]-PN by hydrogenation with palladium.