Synthesis of enantiomerically pure (E)-1,1,3,3,6,6-hexamethyl-1-sila-4-cycloheptene and its absolute configuration

Krebs, Adolf; Thölke, Bernd; Pforr, Karl‐Ingo; König, Wilfried Α.; Scharwächter, Klaus; Vögtle, Fritz; Sobanski, Adam; Schramm, Jörg; Hormes, J.

doi:10.1016/s0957-4166(99)00313-4

Cited by 11 publications

(8 citation statements)

References 13 publications

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“…A calculation of the structural parameters of 2 has been published recently. 20 The experimental and theoretical values obtained for 1-4 are listed in Table 1. At first sight, surprisingly, the C-C spin coupling constants across the double bond in 1 and 2 are identical and of a normal absolute value.…”

Section: Resultsmentioning

confidence: 99%

Experimental and quantum chemical investigation of the stereochemical dependence of spin coupling constants in symmetrical strained alkenes

et al. 2000

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The 13C–13C, 13C–1H and 1H–1H spin coupling constants in some strained symmetrical alkenes were measured using a new gradient selected method. The olefinic 1J(C,C) spin coupling constants were calculated using ab initio and DFT quantum chemical calculations for model compounds. The calculated and experimental data are in good agreement. The olefinic 1J(C,C) spin coupling constants do not reflect the high distortion of the double bond in silacycloheptene 2. This is attributed to the fact that the Fermi contact contribution to the coupling constants is transmitted via the sp2‐type σ‐orbital, whereas the π‐type MO with a nodal plane at the position of the nuclei does not contribute to the 13C–13C coupling. Copyright © 2000 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

Experimental and quantum chemical investigation of the stereochemical dependence of spin coupling constants in symmetrical strained alkenes

et al. 2000

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“…While CNDO/2S performs fairly well as far as the sign and wavelength of the first Cotton effect of the decomposition product is concerned 1 such semiempirical calculations on the CD spectrum of parent rubroflavin did not even qualitatively reproduce the main features of the observed spectrum. Because in the last years time‐dependent density functional theory (TDDFT) has become an important tool for theoretical studies on the chiroptical properties of midsized molecules 3–7 we examined the CD spectrum of parent rubroflavin using this theory. To obtain a calculated CD spectrum of the title compound, we optimized the structures of 30 plausible isomers (quinoid, phenolic, and others)* of rubroflavin with density functional theory (DFT).…”

Section: Introductionmentioning

confidence: 99%

Time‐dependent density functional theory calculations on the chiroptical properties of rubroflavin: Determination of its absolute configuration by comparison of measured and calculated CD spectra

Wang¹,

Raabe²,

Repges³

et al. 2003

Int J of Quantum Chemistry

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ABSTRACT:The absolute configuration of rubroflavin has been determined by comparison of its measured and calculated CD spectra. For this purpose the structures of 30 plausible isomers of the title compound have been optimized with density functional theory (DFT/BP86) using a triple-zeta valence basis set. The absolute (S) configuration at the OS(AO)CH 3 group has been assumed in these calculations. One quinoid isomer, which is separated from all other structures by an energy gap of about 4 kcal/mol, was found to be the most stable species and to dominate the CD spectrum. The structure of this isomer has been reoptimized under the influence of a solvent using an electrostatic model (COSMO). Based on the geometries of the most stable isomer obtained in the presence and absence of the solvent the excitation energies and oscillator as well as rotational strengths have then been calculated using timedependent DFT (TDDFT/TZVP/BP86). Comparison of the measured CD spectrum with that calculated for the energetically lowest isomer shows that especially the long wavelength parts of the spectra agree fairly well as far as the wavelengths and the signs of the Cotton effects are concerned while the correspondence between calculated and measured intensities is less satisfying. The agreement between the measured and calculated spectrum is better if the geometry optimized under the influence of the solvent is used. A detailed analysis of the spectra led us to the conclusion that the absolute configuration of rubroflavin is (S). These results support earlier assignments based on semiempirical and ab initio studies on a thermal decomposition product of rubroflavin.

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“… 45 – 52 In 1997, ( E )-1,1,3,3,6,6-hexamethyl-1-sila-4-cycloheptene was synthesized, resolved, and characterized crystallographically. 46 , 47 Here, the exhaustive allylic substitution imparts a high degree of stability to the trans -alkene. Recent studies by Woerpel 48 – 51 and Tomooka 52 have provided demonstrations of the utility of backbone heteroatom-containing trans -cycloalkene derivatives in synthesis.…”

Section: Introductionmentioning

confidence: 99%

Photochemical syntheses, transformations, and bioorthogonal chemistry oftrans-cycloheptene and silatrans-cycloheptene Ag(i) complexes

et al. 2018

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Synthesis of enantiomerically pure (E)-1,1,3,3,6,6-hexamethyl-1-sila-4-cycloheptene and its absolute configuration

Cited by 11 publications

References 13 publications

Experimental and quantum chemical investigation of the stereochemical dependence of spin coupling constants in symmetrical strained alkenes

Experimental and quantum chemical investigation of the stereochemical dependence of spin coupling constants in symmetrical strained alkenes

Time‐dependent density functional theory calculations on the chiroptical properties of rubroflavin: Determination of its absolute configuration by comparison of measured and calculated CD spectra

Photochemical syntheses, transformations, and bioorthogonal chemistry oftrans-cycloheptene and silatrans-cycloheptene Ag(i) complexes

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