An expedient method for the direct conversion of acyl isothiocyanates to 2,4-disubstitued thiooxazoles and 2,4-disubstituted oxazole sulfonyl chlorides is described. The method takes advantage of an early observation by Sheehan and the reaction of diazomethane with isocyanates to form oxazolones. However, in this case an acyl isothiocyanate is utilized as well as the readily available TMS-diazomethane
The alkylations of 5-acylamino-1,2,3-thiadiazoles (4) have been investigated; the N-3 position is preferably alkylated forming new mesoionic heterocycles (5) and (10). The mesoionic 1,2,3-thiadiazolium-5-alkoxy- and -5-aryloxy-carbonylaminides are converted into the corresponding salts of the 5-imine derivatives (11) by hydrolysis with hydrochloric acid.
7-[.alpha.-(2-Aminomethyl-1-cyclohexyl)-acetamido]-3-heterocyclic thiomethyl-3-cephem-4-carboxylic acids, and their nontoxic, pharmaceutically acceptable salts and their Schiff bases, as made by reaction of salicylaldehyde with the free amino group, are valuable as antibacterial agents and are particularly valuable as therapeutic agents in poultry and animals, including man, in the treatment of infectious diseases caused by many Gram-positive and Gram-negative bacteria.