1.3- Thiazolidine-4-ones

C5H8N2O2S, 5-Ethyl-2-hydroximino-1,3-thiazolidine-4-one, 44B, 354 C5H8N20i,S4, Dimethyl 1,2,5,6-tetrathia-3,4-diazacycloheptane-3,4-di-carboxylate, 42B, 285 C5H9NO3S, Chondrine, 38B, 387... 

In his cephalosporin synthesis methyl levulinate was condensed with cysteine in acidic medium to give a bicyclic thiazolidine. One may rationalize the regioselective formation of this bicycle with the assumption that in the acidic reaction mixture the tMoI group is the only nucleophile present, which can add to the ketone. Intramolecular amide formation from the methyl ester and acid-catalyzed dehydration would then lead to the thiazolidine and y-lactam rings. The stereochemistry at the carboxylic acid a-... 

Alizadeh A, Zohreh N (2009) A novel multicomponent method for the synthesis of 2-thioxo-l,3-thiazolidine -ones. Synlett 2009 2146-2148... 

The reduction of a number of thiazolium salts had been shown to yield diastereomeric mixtures of thiazolidines from which it has been possible, in some cases (including that of thiamine), to isolate one pure species (Schemes 94 and 94a). 

The reaction of phosphorus pentasulfide with a-acylamino carbonyl compounds of type Ilia also yields thiazoles. Even more commonly, a mercaptoketone is condensed with a nitrile of type IVa or a-mercaptoacids or their esters with Schiff bases. This ring closure is limited to the thiazolidines. In the Va ring-closure type, /3-mercaptoalkylamines serve as the principal starting materials, and ethylformate is the reactant that supplies the carbon at the 2-position of the ring. These syntheses constitute the most important route for the preparation of many thiazolidines and 2-thiazohnes. In the Vb t3fpe of synthesis, one of the reactant supplies only the carbon at the 5-position of the resultant thiazole. Then in these latter years new modern synthetic methods of thiazole ring have been developed (see Section 7 also Refs. 515, 758, 807, 812, 822). 

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-... 

Reactions of enamines with isocyanates (568) and isothiocyanates (569) in the presence of sulfur gave l,3-thiazolidine-2-ones and l,3-thiazolidine-2-thiones. 

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 -... 

The related serine derived (4S)-4-methoxycarbonyl-3-(l-oxopropyl)-2-thiono-l,3-oxazolidine 11, and the cysteine derived (4A)-4-methoxycarbonyl-3-(l-oxobntyl)-2-thiono-1,3-thiazolidine 13, also serve as efficient chiral auxiliaries in boron- and tin(II)-mediated aldol condensations98. Thus, conversion of 11 into the boron or tin enolate, followed by reaction with 2-methylpropanal affords predominantly one adduct. Subsequent methanolysis and chromatographic purification delivers the syu-methyl ester in 98% ee. 

Higher degrees of induced stereoselectivity are obtained using the chiral (4,S )-3-acetyl-4-iso-propyl-l,3-thiazolidin-2-one where, once again, the tin enolate is most efficient. 3-Hydroxy ester 12 is accessible in 94% ee by this aldol variation112. 

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... 

Chiral tricyclic fused pyrrolidines 29a-c and piperidines 29d-g have been synthesized starting from L-serine, L-threonine, and L-cysteine taking advantage of the INOC strategy (Scheme 4) [19]. L-Serine (23 a) and L-threonine (23 b) were protected as stable oxazolidin-2-ones 24a and 24b, respectively. Analogously, L-cysteine 23 c was converted to thiazolidin-2-one 24 c. Subsequent N-allylation or homoallylation, DIBALH reduction, and oximation afforded the ene-oximes, 27a-g. Conversion of ene-oximes 27a-g to the desired key intermediates, nitrile oxides 28 a-g, provided the isoxazolines 29 a-g. While fused pyrrolidines 29a-c were formed in poor yield (due to dimerization of nitrile oxides) and with moderate stereoselectivity (as a mixture of cis (major) and trans (minor) isomers), corresponding piperidines 29d-g were formed in good yield and excellent stereoselectivity (as exclusively trans isomers, see Table 3). 

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,... 

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