Vodonična veza u push-pull 5-supstituisanim 2-alkiliden-4-oksotiazolidinima: 1H-NMR spektroskopsko proučavanje

Application of dynamic H-1-NMR spectroscopy added to the understanding of the hydrogen bonds existing in the structurally related 5-substituted-2-alklidene-4-oxothiazolidines in polar and apolar solvents. The equilibrated mixtures of these topical push-pull alkenes in CDCl3 consist of the intramolecularly H-bonded (E)-isomer and intermolecularly H-bonded (Z)-isomer in varying proportions which depend on the solvent polarity. For the representative of the series. (Z)-2-(5-ethoxycarbonylmethyl-4-oxothiazolidin-2-ylidene)-1-phenylethanone, a concentration effect on the degree of intermolecular hydrogen bonding in apolar CDCl3 has been studied.Primenom dinamičke 1H-NMR spektroskopije došlo se do boljeg razumevanja o vrsti vodoničnih veza koje postoje u strukturno sličnim 5-supstituisanim 2-alkiliden-4-oksotiazolidinima u polarnim i apolarnim rastvaračima. Uravnotežene smese ovih tipičnih push-pull alkena u CDCl3 sadrže (E)-izomer vezan intramolekulskom vodoničnom vezom kao i intermolekulski vodoničnom vezom vezan (Z)-izomer u različitim odnosima, koji zavise od polarnosti rastvarača. U slučaju tipičnog predstavnika serije (Z)-2-(5-etoksikarbonilmetil-4-oksotiazolidin- 2-iliden)-1-feniletanona uticaj koncentracije na stepen stvaranja intermolekulske vodonične veze u apolarnom CDCl3 je takođe proučavan

Thermal solid-state Z/E isomerization of 2-alkylidene-4-oxothiazolidines: effects of non-covalent interactions

Configurational isomerization of stereo-defined 5-substituted and un-substituted 2-alkylidene-4-oxothiazolidines (1) in the solid state, giving the Z/E mixtures in various ratios, was investigated by H-1-NMR spectroscopy, X-ray powder crystallography and differential scanning calorimetry (DSC). The Z/E composition can be rationalized in terms of non-covalent interactions, involving intermolecular and intramolccular hydrogen bonding and directional non-bonded 1,5-type S center dot center dot center dot O interactions. X-Ray powder crystallography, using selected crystalline (Z)-4-oxothiazolidine substrate, revealed transformation to the amorphous state during the irreversible Z - gt E process. A correlation between previous results on the Z/E isomerization in solution and now in the solid state was established

Supplementary data for the article: Rašović, A.; Blagojević, V.; Baranac-Stojanović, M.; Kleinpeter, E.; Marković, R.; Minić, D. M. Quantification of the Push-Pull Effect in 2-Alkylidene-4-Oxothiazolidines by Using NMR Spectral Data and Barriers to Rotation around the CC Bond. New Journal of Chemistry 2016, 40 (7), 6364–6373. https://doi.org/10.1039/c6nj00901h

Supplementary material for: [https://doi.org/10.1039/c6nj00901h]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2336

Regioselective reduction of 5-substituted 2-alkylidene-4-oxothiazolidines by metal hydrides

Thiazolidine beta-enamino derivatives possessing a 5-substituted acetate substituent were chemoselectively reduced to corresponding alcohols, or new condensed 2-alkylidenethiazolidines. The method is based on the resistance of an enaminone fragment to reduction by metal hydrides

Thermal solid-state Z/E isomerization of 2-alkylidene-4-oxothiazolidines: effects of non-covalent interactions

Configurational isomerization of stereo-defined 5-substituted and unsubstituted 2-alkylidene-4-oxothiazolidines (1) in the solid state, giving the Z/E mixtures in various ratios, was investigated by 1H-NMR spectroscopy, X-ray powder crystallography and differential scanning calorimetry (DSC). The Z/E composition can be rationalized in terms of non-covalent interactions, involving intermolecular and intramolecular hydrogen bonding and directional non-bonded 1,5-type S×××O interactions. X-Ray powder crystallography, using selected crystalline (Z)-4-oxothiazolidine substrates, revealed transformation to the amorphous state during the irreversible Z®E process. A correlation between previous results on the Z/E isomerization in solution and now in the solid state was established

Stereocontrolled synthesis of new tetrahydrofuro[2,3-d]thiazole derivatives via activated vinylogous iminium ions

Heterocyclization of (Z)-5-(2-hydroxyethyl)-3-methyl-4-oxothiazolidines, bearing electron-withdrawing groups conjugated to an exocyclic double bond at C(2)-position, afforded under reductive conditions, cis-tetrahydroftiro[2,3-d]thiazole derivatives. The reactions of these functionalized push-pull beta-enamines occur in a stereocontrolled fashion via activated vinylogous N-methyliminium ions, which are trapped by an internal hydroxyethyl group

High regioselectivity in the heterocyclization of beta-oxonitriles to 4-oxothiazolidines: X-ray structure proof

Base-catalyzed reactions of beta-oxonitriles 1 with diethyl mercaptosuccinate favour heterocyclization to afford 2-alkylidene-4-oxothiazolidines 3, rather than 2-alkylidene-4-oxo-1,3-thiazinanes 4. The observed regioselectivity is based on spectroscopic and experimental evidence, including a single-crystal X-ray structure determination. (C) 2003 Elsevier Ltd. All rights reserved

An expedient solvent-free synthesis of (Z)-2-alkylidene-4-oxothiazolidine derivatives under microwave irradiation

A new and efficient microwave-assisted synthesis of (Z)-2-alkylidene-4-oxothiazolidine derivatives 4 under solvent-free conditions and without solid support, is described. In comparison to conventional technique, experimental evidence reveals the benefits of the MW-promoted synthesis of functionalized 4-oxothiazolidine derivatives 4 in terms of simple workup, efficiency and safe reproducibility. The method, as environmentally cleaner, was shown to be potentially applicable to similar chemical processes, such as the preparation of not easily obtainable 4-oxo-1,3-thiazinan-2-ylidene derivative 6

An expedient solvent-free synthesis of (Z)-2-alkylidene-4-oxothiazolidine derivatives under microwave irradiation

A new and efficient microwave-assisted synthesis of (Z)-2-alkylidene-4-oxothiazolidine derivatives 4 under solvent-free conditions and without solid support, is described. In comparison to conventional technique, experimental evidence reveals the benefits of the MW-promoted synthesis of functionalized 4-oxothiazolidine derivatives 4 in terms of simple workup, efficiency and safe reproducibility. The method, as environmentally cleaner, was shown to be potentially applicable to similar chemical processes, such as the preparation of not easily obtainable 4-oxo-1,3-thiazinan-2-ylidene derivative 6