New Thiazolo[3,2-b][1,2,4]triazole Derivatives : Useful Compounds for the Preparation of 7-Substituted Cephalosporins

New Thiazolo[3,2-b][1,2,4]triazole Derivatives : Useful Compounds for the Preparation of 7-Substituted Cephalosporins

We have synthesized several bicyclic heteroaromatic compounds with bridgehead nitrogen from N-amine salts of heteroaromatic amines. 2-Amino and 2-unsubstituted thiazolo[3,2-b][l,2,4]triazole derivatives 2a-b were prepared by the cyclization reaction from N-amine salts of aminothiazole-5-yl(N-methoxyimino)acetate with cyanogen bromide and formamidine acetic acid salt, respectively. 2-Methylthiazolo[3,2-b][1,2,4]triazole 2c was obtained from N-acetylated N-amine salt of aminothiazole-5-yl(N-methoxyimino)acetate by the cyclization reaction in the presence of polyphosphoric acid (PPA). 2-Substituted and 2-unsubstituted thiazole[3,2-b][1,2,4]triazole derivatives 2a-c were coupled with 7-aminocephalosporanic acid (7-ACA). Coupled cephalosporin derivatives 1a-c did not have good antibacterial activities in vitro.