6142-13-8Relevant academic research and scientific papers
Synthesis and Characterization of 1,3-Bis-(2-dialkylamino-5-thiazolyl)-Substituted Squaraines and Their 2-(Dialkylamino)thiazole Precursors
Keil, D.,Hartmann, H.
, p. 979 - 984 (2007/10/02)
By condensation of squaric acid (1) with 2-(dialkylamino)-substituted thiazoles 8 a novel type of heterocyclic-substituted squaraines of the general structure 9 was prepared in moderate yield mostly.The squaraines 9 obtained are sparingly soluble in the most organic solvents and exhibit, in these solvents, narrow absorption bands in the visible range at about 620-700 nm.In dispersed form, the absorption bands of the squaraines 9 are, however, broadened and shifted into the NIR region at about 900 nm.These unique properties of the new squaraines 9 suggest the use of these dyes as spectral sensitizers for laser-driven data recording or data storage media. - Key Words: Squaraines/ Squaric acid/ Thiazoles/ Sensitizers
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.
A NEW GENERAL SYNTHESIS OF 2-(N-MONO- AND N-DI-SUBSTITUTED AMINO)THIAZOLES
Brown, Michael D.,Gillon, David W.,Meakins, G. Denis,Whitham, Gordon H.
, p. 1623 - 1626 (2007/10/02)
Although α-mercapto ketones react with cyanamides to give substituted 2-aminothiazoles the yields are satisfactory in only the simplest cases.However, a range of 2-aminothiazoles with substituents on the ring or the exo-nitrogen atom was obtained efficiently by the following one-pot procedure: a solution of an α-mercapto ketone anion was generated by treating an O-ethyl S-2-oxoethyl dithiocarbonate with piperidine at 20 deg C, a cyanamide was added, and the solution was heated for 3-6 h.
2-(N,N-Disubstituted Amino)thiazoles with Electron-withdrawing Groups at Position 5: Prepaeation and Investigation on Structural Features
Birkinshaw, Timothy N.,Gillon, David W.,Harkin, Shaun A.,Meakins, G. Denis,Tirel, Malkom D.
, p. 147 - 153 (2007/10/02)
A convenient procedure for preparing N-mono- and NN-di-substituted cyanamides from cyanogen bromide has been developed.N,N-Disubstituted thioureas, obtained from the cyanamides, were condensed with α-bromo-α-cyanoketones to give 5-cyano-2-(N,N-disubstituted amino)thiazoles and with α-bromo-ketones to give 2-(N,N-disubstituted amino)thiazoles.Substitution in the latter products afforded 5-trifluoroacetyl- and 5-nitro-2-(N,N-disubstituted amino)thiazoles; nitration is greatly facilitated by the presence of a 4-aryl group.The average values of the barriers of rotation of the barriers to rotation of the 2-NR2 groups (ΔG298) in the 5-substituted thiazoles were established by variable temperature 1H n.m.r. spectrometry to be 57.4 kJ mol -1 (5-NO2), 56.2 (5-COCF3), and 51.5 (5-CN).I.r. examination showed that the 5-trifluoroacetyl compounds adopt one rotational form preferentially; this is probably the carbonyl O,S-syn-conformation.
Reactions of 1-alkynyl thiocyanates with nucleophilic reagents. Synthesis of 2,4-disubstituted 1,3-thiazoles
Jong, R.L.P. de,Meijer, J.,Sukhai, R.S.,Bradsma, L.
, p. 310 - 313 (2007/10/02)
Reaction of 1-alkynyl thiocyanates RCC-S-CN (1) with alcohols, phenol or thiols or secondary aliphatic amines in the presence of anhydrous zinc chloride or boron trifluoride diethyl etherate gives mixtures of 2,4-disubstituted 1,3-thiazoles (2), thiocarbonyl compounds (3) (thiono esters, dithio esters or thioamides) and 2-alkylidene-1,3-dithioles (4).In all cases, the 1,3-thiazoles can be obtained in good yields if the proper reaction conditions are applied.Interaction between 1 and lithium dialkylamides LiNR'2 gives the compounds RCC-S-NR'2 (5) (attack on sulfur).With alkoxides R'O1-, the primary attack is on CN: the in termediacy alkynethiolate RCC-S1- subsequently reacts with the alkyl cyanate R'OCN to afford 1-alkynyl sulfides RCC-SR'(6)
