Synthesis of 14 C ‐coniferyl alcohol (4‐hydroxy‐3‐methoxycinnamyl alcohol)

Coniferyl alcohol‐β‐ 14 C or ‐γ‐ 14 C (IVa or IVb) was prepared by the reduction of methyl 4‐acetylferulate‐β‐ 14 C or γ‐ 14 C (IIIa or IIIb) with Vitride‐T reagent [70% (w/v) solution of sodium bis (2‐methoxyethoxy) aluminium hydride in benzene]. Several synthetic methods were compared in the preparation of 4‐acetylferulic acid β‐ 14 C or γ‐ 14 C (IIa or IIb). The synthetic reactions used to optimize the yield of (II) are shown in Fig. 1. These reactions were: 1 A Doebner reaction of malonic acid‐2‐ 14 C with acetyl‐vanillin, followed by acetylation of the ferulic acid. 2 A Perkin reaction of acetylvanillin with acetic anhydride‐1‐ 14 C. The Doebner reaction of acetylvanillin with malonic acid 2‐ 14 C was superior to the other reactions for the preparation of 4‐acetylferulic acid‐β‐ 14 C (IIa) and resulted in a 75% yield. The overall yield of coniferyl alcohol‐β‐ 14 C (IVa) from malonic acid‐2‐ 14 C was 20.6% (Note: When coniferyl alcohol‐γ‐ 14 C (IVb) was the desired product, malonic acid‐1‐ 14 C was used).