L,3-Thiazolidin-2-ones

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. 

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. 

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... 

Evans and coworkers262 demonstrated the utility of bis(oxazolidine)copper(II) complexes 425 as Lewis acid catalysts in Diels-Alder reactions of iV-enoyl-l,3-oxazolidin-2-ones 423 with cyclopentadiene, which gave adducts 424 (equation 128, Table 25). Their best results were obtained using catalyst 425c. Surprisingly, only 30% ee was obtained in the reaction between cyclopentadiene and 17a when catalyzed by 425a. Similar results were obtained for the thiazolidine-2-thione analogs of the iV-enoyl-l,3-oxazolidin-2-ones. 

A chiral recognition was observed in aminolysis of 3-acyl-4(R)-methoxycarbonyl-l,3-thiazolidine-2-thione, a derivative of (R)-cysteine, by racemic amines to give an optically active amide [(S)-excess] and amine [(R)-excess]264). In the reaction of cyclic meso-1,3-diols with chiral N-protected phenylalanyl chlorides, Yamada et al.26S) observed the preferential formation of one of the two possible diastereomeric monoesters, which has been used for the synthesis of optically active steroids 266) and prostaglandins 267). 

One of the earliest preparations of the 1,2,4-dithiazole (30) was by acid treatment of a concentrated aqueous solution of 2-thioxo-l,3-thiazolidin-4-one ( rhodanic acid ) (1842LA(43)76) or of one of its salts Ac20 with the> ammonium salt gave the /V-acetyl derivative (1873CB902). Thermolysis of 2-phenyl-l,3-tbiazoline-4,5-dio ne leads via loss of CO to thiobenzoylisocyanate, which with sulfur or P4S10 yields a dithiazolinethione (Scheme 4D. 

Substituents placed on the phenyl rings of 3-benzyl-2-phenyl-l,3-thiazolidin-4-one affect the electron density surrounding both the methine proton, Hm, at C2, Ha and Hb at C5, and He and Hj at the benzyl C. The electron density changes are also exhibited at the C2, C4, C5 and the benzyl carbons. Correlations for the effects of various substituents in both the 2-Ph and 3-benzyl rings with the H and C chemical shifts, for the aforementioned sites, are discussed using Hanunett a constants. ... 

Thiazolidinone and their derivatives are important heterocyclic compounds due to their broad biological activities such as anti-inflammatory, antiprohferative, anticyclooxygenases (COX-1 and COX-2), antihistaminic, and antibacterial activities. More importantly, some of the 2,3-diaryl-l,3-thiazolidin-4-ones were found to be highly effective against HlV-1 replication. 

Roy, K. and Leonard, J.T (2005) Classical QSAR modeling of anti-HIV 2,3-diaryl-l,3-thiazolidin-4-ones. QSAR Comb. Sci., 24, 579-592. 

Acyl-1,3-thiazolidines-2-ones 1.123 (X = S, R = COOMe), obtained from cysteine methyl ether [261], have been introduced by Mukaiyama and coworkers for use in asymmetric aldol reactions [261, 433, 434, 435], In reactions of related //-acyl-1,3-oxazolidines-2-thiones 1.123 (X = O, R = COOMe), each enantiomer can be obtained either from L- or D-serine [434] and the auxiliaries can easily be recovered by methanolysis. Similarly, //-acyl derivatives of 1.121 (X = S) have been used in asymmetric aldol reactions [429, 436], and //-acyl- 1,3-thiazo-lidinethiones 1.123 (X = S, R = r -Pr) are useful in asymmetric acylation [437] and aldol and related reactions [437, 438], Cleavage of the chiral auxiliary is accomplished by aminolysis with O-benzylhydroxylamine or by reduction with LiAlH.,. ... 

Tin (II) enolates have been widely used by Mukaiyama and coworkers in aldol and Michael reactions. These enolates are generated by action of Sn(OTf)2 on ketones, esters, N-acy -1,3-oxazolidin-2-ones or -l,3-thiazolidin-2-thiones, thi-olesters or dithioesters in the presence of chiral diamines 2.13 (R = CH2NHAr or CH2N(CH2)5) bearing the (S)-proline skeleton [253, 559, 682]. Diastereoiso-meric and enantiomeric excesses observed in these reactions are often excellent. 

Atropisomerism in 3-aryl-2-thioxo-l,3-thiazolidin-4-ones 413,3-aryl-2-thioxoimidazolidin-4-one 414, 3-aryl-2-thioxo-l,3-oxazolidin-4-one 415 have attracted much interest. Atropisomerism was monitored by NMR of the AB spectra of the hydrogen in position 5. 5-Substituted derivatives yielded diastereomers. In the case of a high barrier, separation was performed by chromatography on a chiral support. 

An interesting series of N-(2-halogenophenyl) 2-thioxo-l,3-thiazolidin-4-ones 413d, 413b, 413e, and 413f was separated into enantiomers on... 

One of the simplest aldol condensations is the reaction of benzaldehyde with acetophenone. Iron(iii) chloride hexahydrate in [BMIM][BF4] catalyzes this reaction to give chalcone [239]. This same ionic liquid catalyst combination can also be used in the reaction of benzaldehyde with cyclopentanone and cyclohexanone [240]. The aldol reaction can also be base promoted in ionic liquids such as [BMIM][PF6]. An example is the reaction of benzaldehyde with l,3-thiazolidine-2,4-dione. The authors follow this reaction with methylation of the imide with methyl iodide (Scheme 5.2-104) [241],... 

An analogous series of reactions, exemplified in Schemes 32-34, were found to occur between 3-aminoazirines and other NH-acidic heterocycles. For example, isothiazolones or isothiazolidinones 1,1-dioxides react to form the l,2,5-thiadiazocin-6-one 1,1-dioxides (55) <91HCA1002>, and saccharin combines with 3-aminoazirines to yield the l,2,5-benzothiadiazocin-6-one 1,1-dioxides (58) <92HCA2270>. An example was reported where l,3-thiazolidine-2,4-dione reacted with 3-dimethyl-amino-2-cyclobutaneazirine to yield the l,3,6-thiadiazocin-2,7-dione (57) <90HCA1314>. 

A new methodology for the preparation of phenyliminothiazolidinones has been described. The reaction of maleic anhydride (61) with the thiourea 62 gave the 2-imino-l,3-thiazolidin-4-one 63. If maleimides are treated under similar conditions. 

A convenient one-pot protocol for the synthesis of 2-imino-l,3-thiazolidin-4-ones (86 and 87) was developed by the reaction of amines (84), isocyanates (85), aldehydes, and chloroform in the presence of l,8-diazabicycloundec-7-ene (DBU)/sodium hydroxide as the basic medium under ultrasonic irradiation in high yields (75%-91%) and shorter reaction times (12-15 min) (Schane 8.27) (Mamaghani et al. 2011). 

Neuenfeldt et al. (2011) used ultrasonic power to promote the synthesis of thi-azolidinones (91). 2-Aryl-3-(piperonylmethyl)-l,3-thiazolidin-4-ones (91) were obtained in good yields (60%-92%) from the multicomponent reaction of aromatic... 

Mamaghani, M., Loghmanifar, A. and Taati, M. R. 2011. An efficient one-pot synthesis of new 2-imino-l,3-thiazolidin-4-ones under ultrasonic conditions. Ultrason. Sonochem. 

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