Synthesis of 2-(allylthio)pyrazines as a novel cancer chemopreventive agent.

2-(Allylthio)pyrazine derivatives were designed as a novel cancer chemopreventive agent that functions through selective inhibtion of cytochrome P-450 and induction of phase II enzymes involved in the detoxification of carcinogens. A practical preparation method of 2-(allylthio) pyrazine derivatives was established by the reaction of 2-mercaptopyrazine and allylbromides in the presence of a catalytic antioxidant, DABCO (1,4-diazabicyclo[2,2,2] octane), in dimethylformamide at below 50 degrees C.