New Methods for the Synthesis of 2-Aminothiazolones

Two new methods for the synthesis of 2-aminothiazolones from 2-(4-methoxybenzylthio)acetic acids are described. A single reagent and simple experimental conditions are used in the key tandem deprotection−cyclization process. In the first approach 2-aminothiazolones are directly accessed via cyclization of the corresponding N-acylisothioureas. The second complementary approach provides access to a variety of 2-thiomethylthiazolones via cyclization of N-acyldithioimidates. The product 2-thiomethylthiazolones are then efficiently converted to 2-aminothiazolones via amine displacement.