Conformations of Z- and E-isomers of some chiral (1R,4R)-2-arylidene-p-menthan-3-ones |
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Authors: | Pivnenko N S Vashchenko V V Kutulya L A Doroshenko A O Chepeleva L V |
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Institution: | (1) Institute for Single Crystals, National Academy of Sciences of the Ukraine, 60 prosp. Lenina, 61001 Kharkov, Ukraine;(2) Karazin National University, 4 pl. Svobody, 61077 Kharkov, Ukraine |
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Abstract: | The 1Í NMR method in combination with molecular simulation was used to study conformations of Z- and E-isomers of (1R,4R)-cis-2-(4-methoxyphenyl)benzylidene-p-menthan-3-one. In solutions the Z-isomer, unlike the conformationally uniform Å-isomer, is an equilibrium mixture of chair conformers with the substantial predomination of one form with the axially oriented methyl and equatorial isopropyl groups (75—78%). The enone group is more nonplanar in the Z-isomer than in the Å-isomer. For the isopropyl fragment, the equiprobable existence of trans- and two gauche-rotamers for the Z-isomer and a substantial predomination of gauche-forms in the case of the E-isomer were established. |
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Keywords: | Z- and E-(1R 4R)-2-(4-methoxyphenyl)benzylidene-p-menthan-3-ones 1Í NMR spin-spin coupling constants molecular simulation conformers rotamers |
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