Conformational analysis,spectral and catalytic properties of 1,3-thiazolidines,ligands for acetophenone hydrosilylation with diphenylsilane

2-Aryl- and 2-furyl-4-carboxy-1,3-thiazolidines were synthesized. Their spectral properties were studied, and conformational analysis was performed. It was shown that they exist in solution as an equilibrium of neutral and zwitter-ion forms. The influence of the nature of substitutents and of their location in a benzene ring of thiazolidines as ligands of rhodium complexes on acetophenone hydrosilylation with diphenylsilane was examined. Thiazolidines containing donor substituents in the para-position of the benzene ring were found to be the most effective; maximal asymmetrical induction (55% ee) was reached in the presence of 2-(4-methoxyphenyl)-4-carboxy-1,3-thiazolidine.     

One-Pot Synthesis of Novel 2-Imino-5-Arylidine-Thiazolidine Analogues and Evaluation of Their Anti-Proliferative Activity against MCF7 Breast Cancer Cell Line

An efficient surface-mediated synthetic method to facilitate access to a novel class of thiazolidines is described. The rationale behind the design of the targeted thiazolidines was to prepare stable thiazolidine analogues and evaluate their anti-proliferative activity against a breast cancer cell line (MCF7). Most of the synthesized analogues exhibited increased potency ranging from 2–15-fold higher compared to the standard reference, cisplatin. The most active thiazolidines contain a halogenated or electron withdrawing group attached to the N-phenyl ring of exocyclic 2-imino group. However, combination of the two substituents did not enhance the activity. The anti-proliferative activity was measured in terms of IC₅₀ values using an MTT assay.     

Recyclization reactions of heterocycles

2-Thioxo-4-oxazolidone and thiazolidines containing heteroatom substituants (O, S, and NH) in the 2 and 4 positions are converted to benzimidazole derivatives on reaction with o-phenylenediamine. The direction of these recyclizations depends on the nature of the heteroatom substituents in the 2 and 4 positions of the heteroring.See [1] for communication XX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 666–668, May, 1978.     

Synthesis of 2,3,4,7-tetrahydro[1,4]thiazepines from thiazolidines and β-enaminonitriles

A wide library of 2,3,4,7-tetrahydro[1,4]thiazepines have been prepared by simple heating of thiazolidine and β-enaminonitrile derivatives in acetonitrile. The procedure, whose yields depend on the nature and position of the substituents, gave good results if the substituents were not very bulky but it is less effective when starting from 2-substituted thiazolidines.     

Acylation of the 4,5- and 5,6-double bond isomers of 3-steroidal thiazolidines: The chemical stability of spiro-3-steroidal 4,5- and 5,6-double bond isomers

It has been shown that the 5,6-double bond steroidal thiazolidines can be N-acylated if there is no substituent in the 4'-position on the thiazolidine ring; substituents in the 4'-position of the thiazolidine sterically hinder acylation. On the other hand, the 4,5-double bond steroidal thiazolidine isomers decomposed on attempted acylation. The lability of these 4,5-double bond isomers was attributed to the contribution of a hyperconjugative resonance form to the structure of the 4,5-double bond isomers.     

Basicity of Secondary Penta-2,4-diynylamines and Their Reactions with Phenyl Isothiocyanate

Secondary penta-2,4-diynylamines were synthesized, and their pK _a(MeOH) values were obtained by means of nonaqueous potentiometric titration. The reactions of the amines with phenyl isothiocyanate, leading to 2-(phenylimino)-5-(prop-2-ynilidene)thiazolidines, were studied. The N-butyl- and N-benzylthiazolidines with alkyl substituents at the triple bond, formed by the reactions, undergo autooxidation into thiazolidin-4-ones.     

New Studies on [2+3] Cycloadditions of Thermally Generated N‐Isopropyl‐ and N‐(4‐Methoxyphenyl)‐Substituted Azomethine Ylides

The thermal reaction of 1‐substituted 2,3‐diphenylaziridines 2 with thiobenzophenone ( 6a ) and 9H‐fluorene‐9‐thione ( 6b ) led to the corresponding 1,3‐thiazolidines (Scheme 2). Whereas the cis‐disubstituted aziridines and 6a yielded only trans‐2,4,5,5‐tetraphenyl‐1,3‐thiazolidines of type 7 , the analogous reaction with 6b gave a mixture of trans‐ and cis‐2,4‐diphenyl‐1,3‐thiazolidines 7 and 8 . During chromatography on SiO₂, the trans‐configured spiro[9H‐fluorene‐9,5′‐[1,3]thiazolidines] 7c and 7d isomerized to the cis‐isomers. The substituent at N(1) of the aziridine influences the reaction rate significantly, i.e., the more sterically demanding the substituent the slower the reaction. The reaction of cis‐2,3‐diphenylaziridines 2 with dimethyl azodicarboxylate ( 9 ) and dimethyl acetylenedicarboxylate ( 11 ) gave the trans‐cycloadducts 10 and 12 , respectively (Schemes 3 and 4). In the latter case, a partial dehydrogenation led to the corresponding pyrroles. Two stereoisomeric cycloadducts, 15 and 16 , with a trans‐relationship of the Ph groups were obtained from the reaction with dimethyl fumarate ( 14 ; Scheme 5); with dimethyl maleate ( 17 ), the expected cycloadduct 18 together with the 2,3‐dihydropyrrole 19 was obtained (Scheme 6). The structures of the cycloadducts 7b, 8a, 15b , and 16b were established by X‐ray crystallography.     

Spectral and self-assembly properties of a series of asymmetrical pyrene derivatives

A series of pyrene derivatives with different asymmetrical substituents were successfully synthesized and characterized. The geometrical electronic structures of the asymmetrical pyrene derivatives were performed by density functional theory （DFT） calculations. The results of photophysical spectra and electrochemical analysis indicated that the optical or electric properties of the pyrene derivatives could be tuned by adjust the π-conjugation lengths of the substituents. Furthermore, through a phase exchange self-assembly method, the highly organized morphologies were observed by SEM.     

Reductive opening of the thiazolidine ring. Selective N-methylation of cysteamines

The reaction of thiazolidines 2 and 7 with borane was investigated. It gave N-methylcysteamines 3 and 8 through thiazolidine ring opening. Sodium borohydride and lithium aluminum hydride were ineffective.     

11B Nuclear magnetic resonance study of the reactivity of borane tetrahydrofuran with representative dithianes,diazolidines, thiazolidines,benzothiazolines and benzothiazoles

The reaction of borane tetrahydrofuran with the title compounds led by ring opening to the synthesis of new borolidine heterocycles. ¹¹B NMR not only allowed the observation of borane adducts of dithianes, diazolidines, thiazolidines, benzothiazolidines and benzothioles, but even provides useful information concerning their stereochemistry.     

Reaction of α-halo ketone with 2-aminothiol: a new synthesis of thiazolidines with the oxo group migrated to the original position occupied by halogen atom

The reaction of 2-bromo-3-oxo steroids with 2-aminoethanethiol led to the stereoselective formation of spiro[steroid-3,2′-thiazolidin]-2-ones as the major product. With both cyclic and acyclic α-halo alkanones, the reaction gave the thiazolidines with the oxo group migrated to the original position occupied by the halogen atom. In addition, it was found that the use of microwaves affords improvement of yields and shortening the reaction time in comparison with usual conditions.     

Synthesis of 2-(1-Arylcarbonyl-1-arylazomethylidene)-thiazolidines by the Reaction of 2-(Arylcarbonyl-methylidene)thiazolidines with Diazobenzenes

A variety of 2-(1-arylcarbonyl-1-arylazomethylidene)-thiazolidenes were synthesized in excellent yields by the reaction of 2-(arylcarbonylmethylidene)thiazolidines with diazobenzenes.     

Organocatalytic oxidative dehydrogenation of aromatic amines for the preparation of azobenzenes under mild conditions

(Diacetoxyiodo)benzene used as stoichiometrically and catalytically in the preparation of azobenzenes under mild reaction conditions was developed. The metal-free oxidation systems demonstrated wide substituents tolerance, alkyls, halogens, and several versatile functional groups, such as amino, ethynyl, and carboxyl substituents are compatible well, and the corresponding products could be formed with good to excellent yields. In this disclosed method, the more large scale formation of azo compounds also could be carried out successfully. Of note that 3-ethynylbenzenamine applied as a very useful cross dehydrogenative partner, which coupled with different anilines, providing asymmetrical azo compounds with acceptable yields in one step under very mild reaction conditions.     

Research on unsaturated lactones. 49. Synthesis of thiazolidines that contain an α,β-unsaturated γ-lactone ring

The corresponding thiazolidines containing a lactone ring and their hydrochlorides and N-benzoyl derivatives were obtained by the reaction of 2-acetyl-3,4,4-trimethyl-2-buten-4-olide with thioglycolic or mercaptosuccinic acids and ammonium carbonate.See [1] for Communication 48.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 475–476, April, 1981.     

Biocatalytic Reduction of 2‐Monosubstituted 3‐Thiazolines Using Imine Reductases

The application of a straightforward biocatalytic technology for the reduction of racemic 2‐monosubstituted 3‐thiazolines, which are easily prepared via Asinger‐multicomponent reaction, is reported. The biocatalytic reduction yields racemic 2‐monosubstituted 3‐thiazolidines, which are difficult to be prepared by means of classic chemical routes, in moderate to high yields. Moreover, our study clarifies the stereochemical reaction course of the biocatalytic reduction. Furthermore, the efficiency of this biocatalytic technology is demonstrated in an experiment at an elevated substrate concentration of 60 mM leading to 96% conversion.     

Novel catalytic rearrangements of 2-vinyl-1,3-thiazetidines

The thiazetidines (1) and (2) undergo a novel and high yielding rearrangement on hydrogenation with heterogeneous catalysis to give the thiazolidines (5) and (8) whilst reaction with the homogeneous catalyst Rh(Ph₃P)₃Cl results in the alternative high yielding rearrangement to give a thiazine.     

Highly selective colorimetric sensor for cysteine and homocysteine based on azo derivatives

A simple colorimetric method for the determination of cysteine and homocysteine has been developed. The reaction of the azo dyes containing an aldehyde group with cysteine or homocysteine afforded very stable derivatives thiazolidines or thiazinanes under neutral pH conditions. The method is selective and sensitive for cysteine and homocysteine detection without the interference of other amino acids. Importantly, the recognition of Cys and Hcy could be observed by naked eyes.     

Tautomerism in a number of asymmetrical imidazole systems

It is shown that in NH-unsubstituted asymmetrical imidazole systems the predominant tautomeric forms are those with the proton attached to the heteroatom which is most susceptible to the effect of electron-accepting substituents or least susceptible to the effect of electrondonating substituents.See [7] for the method of analysis of tautomeric equilibria from pK_a data.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1683–1687, December, 1970.     

Novel rhodium-catalyzed reaction of thiazolidine derivatives with carbodiimides

A new, simple, and regioselective synthesis of thiazolidinimine derivatives based on the rhodium-catalyzed reaction of readily available thiazolidines with carbodiimides is described. This methodology provides direct access to a large variety of thiazolidinimine derivatives, possibly via a novel regiospecific insertion of carbodiimides into one of two ring carbon-nitrogen bonds, as well as a metal-catalyzed imine elimination process.     

Reactions of malonodithioamides with acetylenedicarboxylic esters

Reactions of malonothioamides with acetylenedicarboxylates proceed as an addition of the sulfur atom at the triple bond with subsequent intramolecular reaction between the ester group and the nitrogen atom, that leads to substituted thiazolidines. Unsubstituted malonodithioamide and N-cyclohexylmalonodithioamide give adducts involving both thioamide fragments, whereas N,N′-bis(4-methoxyphenyl)malonodithioamide forms the 1: 1 adducts.