Studies on Pyrimidine Derivatives and Related Compounds. LXXX. Unusual Reactions of Thiamine Free Base with Electrophilic Reagents. (2)

抄録

The reaction of thiamine free base (I) with isocyanate derivatives in polar solvent such as dimethylformamide afforded 2- (7-methyl-3, 4-dihydropyrimido [4, 5-d] pyrimidin-3-yl) -2-methyltetrahydrofuran-3-yl alkyl (aryl) carbamthiolate (V), which then reacted with another isocyanate molecule to give N-carbamoylthiamine free base (II). The reaction mechanism is discussed kinetically. The reaction of I with isocyanate derivatives in less polar solvent such as chloroform afforded only II-analogues. The reaction of II with N, N-disubstituted carbamoylchlorides afforded 2- [N-formyl-N- (2-methyl-4-aminopyrimidin-5-yl) methyl] amino-2-methyltetrahydrofuran-3-yl disubstituted carbamthiolates (VIIa-c).