A convenient synthesis of di- and trisubstituted 2-aminoimidazoles from 1-amidino-3-trityl-thioureas

Convenient synthesis of 2-amino-1,5-disubstituted and 2-amino-1,4,5-trisubstituted imidazoles has been reported using readily available starting materials and simple reagents under mild conditions. Guanylation of 1-amidino-3-trityl-thioureas 1 and 7 using mercury(II) chloride (Caution) as a thiophile resulted in corresponding guanidines 2 and 8 which on reaction with α-bromo ketones yielded 2-tritylaminoimidazoles. Deprotection of 2-tritylaminoimidazoles using trifluoroacetic acid at room temperature furnished desired 2-aminoimidazoles 4 and 10 in good to moderate yields.