A series of 5-unsubstituted and 5-substituted 2-alkylidene-4-oxothiazolidine-S-oxides were synthesized by the sulfur-oxidation with m-CPBA. The stereochemistry of 5-substituted sulfoxides was determined by means of NMR spectroscopy and DFT theoretical calculations. It was found that the thermodynamically less stable anti-isomer was initially formed in the course of the oxidation, but it underwent epimerization to the mixture enriched in the more stable syn-isomer, during the work-up process. The higher stability of syn-isomers is ascribed to the stronger hyperconjugative sigma(C-H)->sigma*(S-O) interaction versus the weaker sigma(C-C)->sigma*(S-O) delocalization in their anti-counterparts and to the existence of intramolecular 1,5-CH center dot center dot center dot C hydrogen bonds.
Keywords:
2-Alkylidene-4-oxothiazolidine / Sulfoxide / Diastereoselectivity / Density functional calculations / CH center dot center dot center dot O hydrogen bonds
TY - JOUR
AU - Džambaski, Zdravko
AU - Marković, Rade
AU - Kleinpeter, Erich
AU - Baranac-Stojanović, Marija
PY - 2013
UR - https://cer.ihtm.bg.ac.rs/handle/123456789/1344
AB - A series of 5-unsubstituted and 5-substituted 2-alkylidene-4-oxothiazolidine-S-oxides were synthesized by the sulfur-oxidation with m-CPBA. The stereochemistry of 5-substituted sulfoxides was determined by means of NMR spectroscopy and DFT theoretical calculations. It was found that the thermodynamically less stable anti-isomer was initially formed in the course of the oxidation, but it underwent epimerization to the mixture enriched in the more stable syn-isomer, during the work-up process. The higher stability of syn-isomers is ascribed to the stronger hyperconjugative sigma(C-H)->sigma*(S-O) interaction versus the weaker sigma(C-C)->sigma*(S-O) delocalization in their anti-counterparts and to the existence of intramolecular 1,5-CH center dot center dot center dot C hydrogen bonds.
PB - Oxford : Pergamon-Elsevier Science Ltd
T2 - Tetrahedron
T1 - 2-Alkylidene-4-oxothiazolidine S-oxides: synthesis and stereochemistry
VL - 69
IS - 31
SP - 6436
EP - 6447
DO - 10.1016/j.tet.2013.05.087
ER -
@article{
author = "Džambaski, Zdravko and Marković, Rade and Kleinpeter, Erich and Baranac-Stojanović, Marija",
year = "2013",
abstract = "A series of 5-unsubstituted and 5-substituted 2-alkylidene-4-oxothiazolidine-S-oxides were synthesized by the sulfur-oxidation with m-CPBA. The stereochemistry of 5-substituted sulfoxides was determined by means of NMR spectroscopy and DFT theoretical calculations. It was found that the thermodynamically less stable anti-isomer was initially formed in the course of the oxidation, but it underwent epimerization to the mixture enriched in the more stable syn-isomer, during the work-up process. The higher stability of syn-isomers is ascribed to the stronger hyperconjugative sigma(C-H)->sigma*(S-O) interaction versus the weaker sigma(C-C)->sigma*(S-O) delocalization in their anti-counterparts and to the existence of intramolecular 1,5-CH center dot center dot center dot C hydrogen bonds.",
publisher = "Oxford : Pergamon-Elsevier Science Ltd",
journal = "Tetrahedron",
title = "2-Alkylidene-4-oxothiazolidine S-oxides: synthesis and stereochemistry",
volume = "69",
number = "31",
pages = "6436-6447",
doi = "10.1016/j.tet.2013.05.087"
}
Džambaski, Z., Marković, R., Kleinpeter, E.,& Baranac-Stojanović, M.. (2013). 2-Alkylidene-4-oxothiazolidine S-oxides: synthesis and stereochemistry. in Tetrahedron
Oxford : Pergamon-Elsevier Science Ltd., 69(31), 6436-6447.
https://doi.org/10.1016/j.tet.2013.05.087
Džambaski Z, Marković R, Kleinpeter E, Baranac-Stojanović M. 2-Alkylidene-4-oxothiazolidine S-oxides: synthesis and stereochemistry. in Tetrahedron. 2013;69(31):6436-6447.
doi:10.1016/j.tet.2013.05.087 .
