Abstract
In the course of the development of a new cyan dye-forming coupler skeleton for color photographic use, we found that 1H-pyrrolo [1, 2-b] [1, 2, 4] triazole having electron-withdrawing groups in the 6, 7 positions could promptly couple with oxidized developing agent to form an azomethine cyan dye. 6-Cyano and 7- (2, 6-di-tert-butyl-4-methyl) cyclohexyloxycarbonyl groups were essential to obtain an excellent hue and stability of the dye. The following synthetic breakthroughs were achieved to lead 1H-pyrrolo [1, 2-b] [1, 2, 4] triazoles to practical couplers. (1) Highly bulky alcohol (Magic alcohol) was efficiently synthesized via two-step reduction of 2, 6-di-tert-butyl-4-methylphenol. (2) Efficient synthesis of highly bulky ester (Magic ester) was accomplished by way of a ketene intermediate generated from triazolylacetic acid derivative. (3) Two types of novel cyclization reactions were developed to construct 5-unsubstituted and 5-acyloxy 1H-pyrrolo [1, 2-b] [1, 2, 4] triazoles from triazole derivatives.
