A new method for preparation of 1-(4-substituted phenyl)-6-phenyl-2-thiouracils via cyclization of N-(4-substituted phenyl)-N'-3-phenylpropenoylthioureas and Dimroth rearrangement of 2-(4-substituted phenylimino)-6-phenyl-5,6-dihydro-4H-1,3-thiazin-4-ones

Abstract

N-(4-Substituted phenyl)-N'-3-phenylpropenoylthioureas treated with lithium hydride afforded 1-(4-substituted phenyl)-6-phenyl-2-thiouracils; these could also be obtained by Dimroth rearrangement of 2-(4-substituted phenylimino)-6-phenyl-5,6-dihydro-4H-1,3-thiazin-4-ones under the same reaction conditions. 2-(4-Substituted phenylimino)-6-phenyl-5,6-dihydro-4H-1,3-thiazin-4-ones were synthesized from the corresponding thioureas under catalysis of boron trifluoride in chloroform.