3- thiazolidin-2-ones

Thiazolines and thiazolidines may also be prepared in this fashion, the structure of the final product determining the substitution pattern to be chosen in the reaction components. Reaction of ethyl bromoacetate with the substituted thioamide (71) resulted in formation of the thiazolidin-4-one (72) (70KGS1621). 

The reactions of the benzenesulfonyl ester of mandelonitrile (177) provide another illustration of the masked bielectrophile approach. On reaction with a primary thioamide the 4-aminothiazole (178) was obtained and this is a convenient route to these derivatives. With a thiourea, the thiazoline (179) was the initial product, and this on treatment with water gave the thiazolidin-4-one (180) (61JOC2715). 

Thiazolidin-4-one, 5-carboxymethyl-synthesis, 6, 317 Thiazolidin-4-one, 2-imino-synthesis, 6, 316 ThiazoIidin-4-one, 2-thioxo-... 

Papers dealing with this topic are exhaustively reviewed in Comprehensive Heterocyclic Chemistry I (84CHEC-I(6)235) and II (96CHEC-II(3)373). Nevertheless, little information is available on the 5-oxides. Recently, the heteroaromaticity of thiazole compared with isothiazole and thiadiazole 5,5-dioxide systems was studied (97MI1). Quantum-chemical calculations and X-ray studies were performed on 3,3 -di[l,3-thiazolidin-4-one] derivatives (95JCC(25)589) studied for their potential biological activity (97FA(52)43). 

Diaryl-thiazolidin-4-one 5,5-dioxides 162 were obtained by reacting thioglycolic acid with Schiff bases, followed by oxidation at the sulfur atom... 

Chemical Nama 2-Carbethoxymethylene-3-methyl-5-piperidino-thiazolidin-4-one ester Common Nama -... 

PhsSnflV)] carboxylates and of some 1 1 addition compounds of PhsSnCl and 2,3-disubstituted thiazolidin-4-ones indicate that the carboxylates in the solid state are monomeric with a Sn atom = 2.14—2.54 mm s the only exception being the furan-2-carboxylic acid derivative, which is polymeric. The PhsSnCl adducts are Thp (I Ag p I = 2.97-3.08 mm s ) with the three Ph groups in a not coplanar eq plane. These complexes are effective inhibitors of C. The 2,3-disubstituted... 

Starting with 2-hydroxycarbohydroxamic acids and ImSOIm, 3-alkoxy-1,2,3-oxa-thiazolidine-4-one 2-oxides or l-alkoxy-3-arylindoline-2-ones can be obtained depending on the substituents at C-2 of the hydroxamic acid [U91... 

The group of Bolognese has disclosed a synthesis of thiazolidin-4-ones by condensation of benzylidene-anilines and mercaptoacetic acid (Scheme 6.215 a) [386]. The authors found that microwave heating of an equimolar mixture of the two components in benzene at 30 °C for just 10 min provides excellent yields of the thiazol-idin-4-one heterocycles. Surprisingly, when the same transformation was carried out at reflux temperature (80 °C), much longer reaction times (2 h) were required and the products were obtained in significantly lower yields (25-69%). 

More recently, Miller and coworkers have reported a one-pot protocol for the preparation of thiazolidin-4-ones by condensation of aromatic aldehydes, amines, and mercaptoacetic acid in ethanol (Scheme 6.215 b) [387]. The optimized procedure involved microwave irradiation of a mixture of the amine hydrochloride, aldehyde,... 

Reaction of isothiocyanate with amine gives the corresponding thioureas. Many reports are appeared.102 111 The thiourea derivatives have been prepared by reactions of isothiocyanates with arylamines (Scheme 39) and reacted with some substrates to afford heterocyclic compounds, such as 2-amino-4//-ben-zothiazine, 1,3-thiazine, 1,3-thiazinone and l,3-thiazolidin-4-one.112 115... 

Imino-thiazolidin-4-ones have been synthesized from alkyl trichloro-methylcarbinols and thiourea in the presence of base (Scheme 56).138... 

Very interestingly, similar l,2-thiazolidin-4-ones 300 behave differently in a basic medium, reacting with sodium hydroxide to give thiazolo[3,4-A][l,2,4]triazoles 134 (Equation 46) <1996JCR(S)388, 2003PS(178)1175>. 

However, the cyclodehydration of 3-[2-aryloxymethyl-l,3,4-oxa(thia)diazol-5-yl]imino-spiro(cyclohexane)l,2-thiazolidin-4-ones 301 with concentrated sulfuric acid at 0°C furnishes tricyclic derivatives 302 (Equation 47) <2002IJC(B)1314>. 

The catalysed alkylation of l//,4//-pyrazol-5-ones is solvent dependent. In benzene, bis-alkylation occurs at the 4-position whereas, in a carbon disulphide benzene mixture, O-alkylation is observed, although the major product (4, Scheme 5.22) results from nucleophilic attack by the pyrazolone on the carbon disulphide, followed by alkylation of the dithiolate dianion [92]. The catalysed reaction of 2-thiono-3-aryl-thiazolidin-4-ones with alkylating agents under soliddiquid two-phase conditions results in alkylation at the 5-position (60-80%) [93]. The aldol condensation of the thiazolidinones with aryl aldehydes is also catalysed by quaternary ammonium salts. 

By the addition of 2-sulfanylacetic acid to the open tautomeric form of tetrahydro-l,3-oxazines, 3-(3-hydroxypro-pyl)thiazolidin-4-ones were obtained in moderate to good yields. The process proved to be slower than the analogous reactions of oxazolidines <2006RJ01101>. 

Extrusion of sulfur dioxide from l,3-thiazolidin-4-ones 1,1-dioxides (17) can be used in the synthesis of [3-lactams (83JOC494). 

Thiazolidin-4-ones have been prepared by condensation of support-bound imines with a-mercapto carboxylic acids (Entry 11, Table 15.18). These thioaminals are quite stable and tolerate, for example, treatment with TFA [228,229]. Thiazolidines, which can be prepared from resin-bound cysteine and aldehydes (Entry 12, Table 15.18), are also remarkably stable towards acid-promoted hydrolysis. Libraries of thiazolidinones have been used to identify new cyclooxygenase-1 inhibitors [230]. 

The reactions of carbon disulfide with compounds 191 under phase-transfer catalysis (PTC) conditions followed by the reaction of the formed intermediate with 5,5-dibromo-3-phenyl-2-thioxo-thiazolidin 4-one 192 gave spiro-1,3-dithietane derivatives 193 (Scheme 23) <1997PS173>. 

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