Syntheses of deuterated 3'-hydroxymethyl-4-(dimethylamino)-azobenzene and related compound

3'-Hydroxymethyl-4-(dimethylamino) azobenzene (I), a new potent hepatocarcinogen, and 3,3'-bis(hydroxymethyl) azobenzene (II) were labeled with multiple-deuterium for the purpose of investigating their metabolisms by the ion cluster technique. I-d4 was obtained in a 22% yield from benzoic-d5 acid (99 atom % D) by nitration, catalytic hydrogenation, reduction, and coupling of the diazonium salt with N,N-dimethylaniline and its deuterium content was 99 atom%. On the other hand, II-d8 was obtained in a 7% yield from 3-nitrobenzoic-d4 acid by reduction and was 91 atom% D.