George F. Taylor

Synthesis of [benzyl-7-3H] and [benzoyl-7-14C] methyl 4-(2,5-dihydroxybenzylamino)benzoate

4-Amino[7-14C]benzoic acid (3) is prepared by carbonation of the lithium salt of N,N-bis(trimethylsilyl)aniline. The methyl ester (4) of 3 is generated with trimethylsilyldiazomethane, and 4 is coupled with 2,5-dihydroxybenzaldehyde to yield methyl 4-(2,5-dihydroxy-benzylimino)[7- 14 C]benzoate (5). 5 is reduced with sodium cyanoborohydride to give methyl 4-(2,5-dihydroxybenzylamino)[7- 14 C]-benzoate with a specific activity of 38.9 mCi/mmol. Unlabeled 5 is reduced with tritium gas to give methyl 4-(2,5-dihydroxy[7- 3 H]-benzylamino)benzoate with specific activity of 7.6 Ci/mmol.