Thiazolic reaction

Pyrrolo[3,4-d]thiazole-4,6-dione, 5-ethyl-2-phenylazo-synthesis, 6, 1005 Pyrrolof 1,2-c]thiazoles reactions, 6, 1040 synthesis, 6, 988, 1047 Pyrrolo[2,1 - ijthiazoles synthesis, 6, 293, 992 1 /7,3/7-pyrrolo[l,2-c]thiazoles synthesis, 6, 1006 Pyrrolo[3,2-d]thiazoles synthesis, 6, 1009... 

Thiazole N-oxides (112 R1=CH3,R2=Ph R1sPh,R2=Me R1 = 4-010, R2=Me 1=4- ,R2sMe) react with isocyanates, XCgH,jNCO(X=H,2-Cl,4-Cl,2-Br,4-Br), to yield bis-(5-imidazolyl)disulphides. Mass spectral results were discussed in detail 2 . Due to space constraints, no attempt has been made to comprehensively cover thiazole reactions or preparations. Those reported are either representative or of special interest. Many patents have been excluded. 

This reaction was first reported by Hantzsch and Weber in 1887. It is the formation of thiazole derivatives by means of condensation of a-haloketones (or aldehydes) and thioamides. Therefore, it is generally known as the Hantzsch thiazole synthesis. In addition, other names, including the Hantzsch synthesis, Hantzsch reaction, and Hantzsch thiazole reaction are also used from time to time. Besides thioamides, other thio-ketone derivatives such as thiourea, dithiocarbamates, and ketone thiosemicarbazone can also condense with a-halo ketones (or aldehydes) to form thiazoles. This reaction occurs because of the strong nucleophilicity of the sulfur atom in thioamides or thioureas, and normally gives excellent yields for simple thiazoles but low yields for some substituted thiazoles, as of dehalogenation. This reaction has been proven to be a multistep reaction, and the intermediates have been isolated at low temperatures, in which the dehydration of cyclic intermediates seems to be the slow step. It is found that a variety of reaction conditions might result in the racemized thiazoles that contain an enolizable proton at their chiral center, and it is the intermediate not the final product that is involved in the racemization. Therefore, some modifications have been made to reduce or even eliminate the epimeriza-tion upon thiazole formation. In addition, this reaction has been modified using a-tosyloxy ketones to replace a-haloketones. ... 

The Hantzsch dihydropyridine synthesis was first reported by Arthur Rudolf Hantzsch in 1881. The Hantzsch pyrrole and thiazole reactions were reported in the years following Hantzsch s initial report on the synthesis of dihydropyridines. 

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