6142-08-1Relevant articles and documents
Electrophilic Substitution at C(5) of 2-Dimethylaminothiazoles
Mahon, Catherine M.,Meakins, G.D.
, p. 2083 - 2090 (2007/10/02)
The reactivity of a series of 4-substituted 2-dimethylaminothiazoles towards electrophiles has been examined.Acetic anhydride reacts only slowly with these thiazoles, with trichloroacetyl chloride and trifluoroacetic anhydride substitution at C(5) occurs readily.The rate of trichloroacetylation is influenced, but not to a marked extent, by changing the 4-substituent.In the presence of acid the thiazoles are deuteriated at C(5), and this reaction is much more sensitive to the nature of the 4 substituents.Estimated p Ka values of the thiazoles were used in evaluating rate constants which although only approximate, provide quantitative information about the effect of particular substituents.
N,N-Disubstituted 2-Aminothiazole-5-carbaldehydes: Preparation and Investigation of Structural Features
Gillon, David W.,Forrest, Ian J.,Meakins, G. Denis,Tirel, Malcolm D.,Wallis, John D.
, p. 341 - 348 (2007/10/02)
Methods of preparing N,N-disubstituted 2-aminothiazoles have been investigated. 4-Substituted N,N-dimethyl-, N-benzyl-N-methyl-, and N-methyl-N-phenyl-amines were prepared and converted by Vilsmeier formylation into 2-amino-5-carbaldehydes which were examined by i.r. and 1H n.m.r. spectrometry.The aldehyde group adopts the carbonyl O,S-syn-conformation.With the N,N-dimethyl and N-benzyl-N-methyl compounds the barrier to rotation of the amine group (ΔG(excit.)) is 50-55 kJ mol-1 and is insensitive to the nature of the 4-substituent.The amine group of the N-methyl-N-phenyl compounds has a marked preference for one orientation.This was shown by a crystallographic study of 4-t-butyl-2-(N-methyl-N-phenylamino)thiazole-5-carbaldehyde to have the phenyl group directed towards the sulphur atom of the thiazole ring.