Synthesis of [3,4,8-13C3]daidzein

The biological effects of the soy isoflavones have attracted considerable interest in recent years leading to numerous studies on dietary intake and epidemiology. Such studies require accurate and reproducible analytical methods. Herein we report the first synthesis of a multiply 13C-labelled daidzein derivative, [3,4,8-13C3]daidzein, which has been employed as an internal standard in LC-MS and GC-MS analysis. The synthesis includes an improved three-step method for the synthesis of [2-13C]resorcinol as one building block.