کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1347282 | 980303 | 2009 | 13 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Chiraloptical properties of adducts derived from cyclic nitrones and 2(5H)-furanones. Combined experimental and theoretical studies
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موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی معدنی
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چکیده انگلیسی
The validity of the Bucourt-Legrand empirical rule, which relates the configuration at the α-carbon atom in the lactone unit with the sign of the lactone nâÏâ transition observed in the electronic circular dichroism (ECD) spectrum of 5-5-5 and 5-5-6 fused heterocyclic systems, was investigated. For this purpose, a combination of ECD spectroscopy, time-dependent density functional theory (TD-DFT) and molecular modelling calculations supported additionally by X-ray diffraction analysis, was applied. Model compounds were obtained via the 1,3-dipolar cycloaddition of 2(5H)-furanones and five- and six-membered cyclic nitrones. In addition, cycloadducts either with or without an additional interfering chromophore were selected. A comparison of the recorded ECD spectra with those simulated by the TD-DFT calculations gave a reasonable interpretation of the excitations observed in the 210-230 nm spectroscopic range. Generally, calculations confirmed the validity of the Bucourt-Legrand rule and demonstrated that ECD may be used as a highly sensitive probe for the three-dimensional molecular structure of the systems studied herein. Notable behaviour, however, was observed in the case of some 5-5-6 fused systems substituted with BnO group. In these cases, the conformational liability and coupling of molecular lactone excitation with other chromophores cause a change of orientation of the transition dipole moments resulting in a breakdown of the rule.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Tetrahedron: Asymmetry - Volume 20, Issue 15, 12 August 2009, Pages 1778-1790
Journal: Tetrahedron: Asymmetry - Volume 20, Issue 15, 12 August 2009, Pages 1778-1790
نویسندگان
Sebastian Stecko, Jadwiga Frelek, Marek Chmielewski,