Thiazoles 2-halogeno— from

The Hantzsch thiazole synthesis from thioamides and a-halogeno-ketones has been applied to iVAr-(dimethyl)dithio-oxamide to give 2-(dimethylthio-carbamoyl)thiazoles, but in some cases it took another course. Thus, 1-alkylthiocarbamoyl-l-cyanoacetophenones (91) react with bromo-ketones with elimination of alkylamine, giving 2-methylidene-l,3-oxathioles (92). The thio-anilide of acetoacetic acid reacts with 2-bromo-l-tetralone to give the spiro-... 

In this chapter we intend to outline the general methods by which the thiazolic ring is synthetized from open-chain compounds. The conversion of one thiazole compound to another is not discussed here, but in appropriate later chapters. Thus the conversion of thiazole carboxylic acids, halogeno-, amino-, hydroxy-, and mercaptothiazoles, to the corresponding unsubstituted thiazoles is treated in Chapters IV through VII, respectively. 

Simple isothiazole-4-carboxylic acids have been made from the corresponding nitriles, which are available in turn from the halogeno derivatives, or directly by the olefin route.5-Aminoiso-thiazole-4-esters and -nitriles are readily obtained by the thioamide route. The 4-acids behave normally and form acid chlorides, esters, amides, and hydrazides. In contrast to the 5-series... 

Structures comprising One Five-Membered Ring and One Seven-Membered Ring (5,7).- Thiazolo-[3,2-a]- and -[4,5-e]-diazepines [C3NS-CSN2]. Thiazolo[3,2-a][l,3]diazepines (154) may be obtained from the reaction between a l,3-diazepine-2-thione and a-halogeno-ketones, and the thiazolo-[4,5-e][l,4]diazepines (155) by the cyclization, under basic conditions, of the thiazoles (156). ... 

This reasoning is supported by the observation that the reaction of 2-nitrofuran with trichloromethyl carbanion proceeds in both 3- and 5-positions, because in this case the base-induced p-elimination of HCl from the intermediate o adducts is a fast process [54]. Also the VNS reactions of nitro derivatives of other 5-membered heterocycles, imidazoles [20, 56] and thiazoles [34], with a variety of a-halogeno carbanions have been shown to proceed efficiently. 

Hantzsch s synthesis of A -thiazolines, like that of thiazoles (see this voL, p. 567), has been shown to involve isolable intermediate 4-hydroxy-hetero-cycles. A series of 3,4-dialkyl-A -thiazoline-2-thiones (162) were prepared from N-alkyldithiocarbamates and a-halogeno-ketones or -aldehydes in this work the stereochemical course of this reaction was elucidated (see... 

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