N,N,N′,N′-tetramethylguanidine has been added to methyl and phenyl isothiocyanates. Reaction of the adducts with α-haloketones has yielded 5-acyl-2-(substituted) amino-4-dimethylaminothiazoles.

Amidinothioureas (7), (11) and (12) obtained by condensation of N,N-disubstituted thioureas with amide acetals have been used as starting materials for the synthesis of thiazoles. Thus, reaction with chloracetone and phenacyl bromides leads to ketones; the use of chloracetic ester in this reaction yields the thiazole-5-carboxylic ester (10).

2-Chloromethyl pyridine, 2-chloromethyl quinoline and 2-chloromethyl benzimidazole have been reacted with amidino thioureas to provide the corresponding 2-amino-5-(2-heteroaryl) thiazoles. 4-Chloromethyl thiazole failed to undergo this reaction.

Careful reaction of equimolar amounts of 1, 3-dichloroacetone and the amidinothioureas (4), (5), (6) or (10) has given the (2-amino-5-thiazolyl) chloromethyl ketones (7), (8), (9) and (11) respectively in 20 to 40% yields. The presence of excess amidinothiourea in the reaction mixture leads to the bis thiazolyl ketones (3).