Versatile assembly of 5-aminothiazoles based on the Ugi four-component coupling

A flexible route to novel 5-aminothiazoles has been developed based on cyclisation of diamide adducts, prepared using the Ugi reaction, in the presence of Lawesson's reagent. The Walborsky reagent (1,1,3,3-tetramethylbutyl isocyanide) was used as the isonitrile component, facilitating subsequent deprotection of the N-alkyl group to yield free 5-aminothiazoles, which were prepared with a variety of substituents at the 2- and 4-positions.