Syntheses of Heterocyclic Compounds of Nitrogen. CXXVII: Photosensitizing Dyes. (21)

Dyes having 4-substituted 2, 5-dimethylthiazole ring as the parent skeleton were synthesized and their antibacterial activity was compared with those of dyes having oxazole ring as the parent skeleton. The compounds prepared were 14 kinds of styryl-type dyes with a thiazole ring and 17 kinds of aminovinyl-type dyes possessing isobutyl or methyl group in 4-position. In general, when compared in the same type of dyes, those possessing a thiazole ring generally had stronger antibacterial action than those with oxazole ring. This is in agreement the general tendency found in the past. Synthesis of thiazoles was carried out with the quaternary salts of 2, 5-dimethyl-4-isobutylthiazole from 3-acetamido-5-methyl-2-hexanone, derived from dl-leucine, and of 2, 4, 5-trimethylthiazole from 3-acetamido-2-butanone, derived from dl-alanine. These quaternary salts were condensed with aromatic aldehydes or formamidine to obtain the dyes.