A solution of α-[[(2,4,6-trimethoxyphenyl)amino]carbonyl]-benzene acetic acid (46.73 g, 0.1353 mol), and 1,1'-carbonyldiimidazole (24.7 g, 0.152 mol) in dry THF (1.0 L) was stirred at room temperature under nitrogen for 2 hours. A white solid precipitated. To the suspension was added tridecanoic acid hydrazide (30.90 g, 0.1353 mol), and the mixture was stirred at room temperature for 17 hours, then at 40° C. for 21 hours. The mixture was chilled (+5° C.) and filtered. The filtercake was washed (THF, ether, water) and dried under house vacuum/air stream; yield 54.36 g (72%); mp 175°-180° C.
