New chiral spiro[2.5]octanones as products of methylenation of (3<Emphasis Type="Italic">R</Emphasis>, 6<Emphasis Type="Italic">R</Emphasis>)-2-arylidene-6-isopropyl-3-methylcyclohexanones with dimethylsulfoxonium methylide. Synthesis,stereochemistry, and behavior in liquid-crystalline systems |
| |
Authors: | I M Gella N S Pivnenko L A Kutulya T G Drushlyak A Yu Kulikov N B Novikova |
| |
Institution: | (1) Scientific Technological Complex “Institute of Single Crystals,”, National Academy of Sciences of Ukraine, 60 prosp. Lenina, 61001 Kharkov, Ukraine;(2) V. N. Karazin Kharkov National University, 4 pl. Svobody, 61007 Kharkov, Ukraine;(3) Scientific Experts Dispensatory Center, 33 ul. Astronomicheskaya, 61085 Kharkov, Ukraine |
| |
Abstract: | Methylenation of (3R,6R)-2-(4-X-benzylidene)-6-isopropyl-3-methylcyclohexanones (X = F, Cl, Ph) with dimethylsulfoxonium methylide occurs stereoselectively
to give 1(S)-(4-X-phenyl)-5(R)-isopropyl-8(R)-methyl-3(R)-spiro2.5]octanones, whose stereochemistry was established by 1H NMR spectroscopy. The configuration of the chiral centers in the cyclohexanone fragment and its preferred conformation (methyl
is axial and isopropyl is equatorial) in the products do not change with respect to the starting enones. The mutual trans-arrangement of the carbonyl and aryl groups at the newly formed three-membered ring was established; the aryl group also
occupies the trans-position with respect to the axial methyl group of the cyclohexanone fragment. Using methylenation of the compound with X
= Ph as an example, a mixture of by-products resulting from oxidative hydroxylation at the α-position relative to the carbonyl
group was isolated. The resulting chiral spiro2.5]octanones induce a helical supramolecular ordering in the nematic mesophase
of 4-pentyl-4′-cyanobiphenyl and exhibit a twisting power only somewhat (by 20–30%) lower than the starting enones.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2331–2341, October, 2005. |
| |
Keywords: | (3R 6R)-2-arylidene-6-isopropyl-3-methylcyclohexanones methylenation dimethylsulfoxonium methylide cyclopropanation (1S 3R 5R 8R)-1-aryl-5-isopropyl-8-methyl-3-spiro[2 5]octan-4-ones 1H NMR spectroscopy induced cholesteric liquid-crystalline systems twisting power |
本文献已被 SpringerLink 等数据库收录! |
|