Facile synthesis of deuterated and [(14) C]labeled analogs of vanillin and curcumin for use as mechanistic and analytical tools.

Curcumin is a dietary diphenol with antioxidant, antinflammatory, and antitumor activity. We describe facile procedures for the synthesis of [(14) C2 ]curcumin (4 mCi/mmol), [d6 ]curcumin, [d3 ]curcumin, [(13) C5 ]curcumin, and [d6 ]bicyclopentadione, the major oxidative metabolite of curcumin. We also describe synthesis of the labeled building blocks [(14) C]vanillin, [d3 ]vanillin, and [(13) C5 ]acetylacetone. The overall molar yields of the labeled products were 52 ([(14) C]) and 47% ([d3 ]) for vanillin and 25 ([(14) C2 ]) and 27% ([d6 ]) for curcumin. The compounds can be used as radiotracers in biotransformation studies and as isotopic standards for mass spectrometry-based quantification in pharmacokinetic analyses.