38650-46-3Relevant academic research and scientific papers
Effect of substituents on the regioselectivity of the reaction of α-tosyloxyketones with thioureas in acidic medium: Access to 2-aminothiazoles and 2-imino-2,3-dihydrothiazoles
Aggarwal, Ranjana,Kumar, Rajiv,Sanz, Dionisia,Claramunt, Rosa M.
, p. 598 - 603 (2014/06/10)
Regioselective condensation of α-tosyloxyacetophenones 1 and N-substituted thioureas 2 in acidic medium to give regioisomers 2-aminothiazoles I and 2-imino-2,3-dihydrothiazoles II is largely influenced by the substituents present on 1 and 2. A mechanism,
The Hantzsch Thiazole Synthesis under Acidic Conditions: Change of Regioselectivity
Bramley, (Miss) Susan E.,Dupplin, Viscount,Goberdhan, Dhanesh G. C.,Meakins, G. Denis
, p. 639 - 644 (2007/10/02)
The condensation of α-halogeno ketones with N-monosubstituted thioureas in neutral solvent leads exclusively to 2-(N-substituted amino)thiazoles.In the present work it was shown that under acidic conditions mixtures of 2-(N-substituted amino)thiazoles and 3-substituted 2-imino-2,3-dihydrothiazoles are formed. (The isomers were distinguished by characteristic differences between their 5-H 1H n.m.r. signals and the i.r.CO bands of their trifluoroacetate derivatives.) The proportions of the 2-imino-2,3-dihydrothiazoles in the mixtures are influenced by experimental features and by the structures of the starting materials.Reactions in 10 M-HCl-EtOH (1:2) at 80 deg C for 20 min were found to be the most efficient for generating 2-imino-2,3-dihydrothiazoles; in the most favourable case 2-imino-3,4-dimethyl-2,3-dihydrothiazole was obtained in 73 percent yield.A possible explanation of the results is discussed.
