Imidazo[2,1-b]thiazolium salts based on 2-phenylamino-4-methylthiazole

Abstract

Among derivatives of imidazo [2,1-b]thiazole are found compounds possessing antiinflammatory [1][2][3], analgesic [4], hypoglycemic [5], antihistamine [6], as well as immune-promoting [7] action. One of the main methods for the synthesis of derivatives of the given heterocyclic system is based on the reaction of 2-aminothiazoles with different halogenoketones [6, 8, 9].In the continuation of investigations [10] into the properties of N-substituted heterocyclic amidines, the reaction of 2-phenylamino-4-methylthiazole (I) with substituted phenacyl bromides led to the synthesis of intermediate compounds --2-phenylimino-3-acylaryl-4-methylthiazoline hydrobromides (IIa-e), which can exist in the two tautomeric forms A and B [11].Analysis of the data of PMR and IR spectra (see Tables 1 and 2 In fact, the protons of the methylene group of the phenacyl substituent in the PMR spectra of the hydrobromides of compounds (IIa-e) appear as a singlet in the region of 5.93-6.06 ppm, whereas the characteristic signals of the AB-system could be expected when the structure B is realized owing to the presence of an asymmetric center. Moreover, the IR spectra contain characteristic bands of stretching vibrations of the CO group in the region of 1680-1705 cm -1, which confirms the structure A.Chemigov Technological Institute, Chemigov 250027.

The Chemistry of α‐Haloketones and Their Utility in Heterocyclic Synthesis

“…Various ring systems containing the -C(NH 2 )=N-moiety as a part of the ring have been found to condense with α-bromoketones to yield condensed imidazo-heterocyclic systems; the ring nitrogen attacks the CH 2 Br unit rather than the primary exocyclic amino group and imidazo[1,2-b]pyrazoles [254,255], imidazo[1,2-a]benzimidazoles [256][257][258][259], imidazo[2,1-b]oxazoles [260], imidazo-[2,1-b]thiazoles [261][262][263][264][265][266][267], imidazo[2,1-b]-1,3,4-thiadiazoles [268][269][270][271][272], imidazo [1,2-d]tetrazoles [273,274], are the well-known condensed imidazo-heterocyclic systems thus prepared. A general systematic preparative route for such fused imidazoles 126 can be presented starting from 124 (Scheme 34).…”