Enantioselective synthesis of chiral liquid crystalline compounds from monoterpenes
摘要:
Chiral liquid crystalline compounds 1-9 have been synthesized enantioselectively from monoterpenes. The optical purities of (S)-(-)- and (R)-(+)-perillalcohol (16, 27). (S)-(-)- and (R)-(+)-1-pentyl-4-hydroxymethyl-1-cyclohexene (33, 34) and (2S,5S)-2-pentyl-5-hydroxymethyl-1-cyclohexanone (53) have been determined by H-1 NMR analysis using chiral shift reagents. The mesomorphic phases and transition temperatures of compounds 2,3,5,6,7,8 and 9 have been characterized.
carbodiimides in hydroxylic solvents containing hydrogenperoxide with mildly basic or acidic catalysts have been found to promote the epoxidation of olefins. A commercially available 30% aqueous solution of hydrogenperoxide serves as the oxidant for this process. The presumed reactive species is a peroxyisourea generated in situ by the addition of hydrogenperoxide to the carbodiimide.
A straightforward methodology for the synthesis of anti‐Markovnikov‐type alcohols is presented. By using a specific cobalt triphos complex in the presence of Zn(OTf)2 as an additive, the hydrogenation of epoxides proceeds with high yields and selectivities. The described protocol shows a broad substrate scope, including multi‐substituted internal and terminal epoxides, as well as a good functional‐group
Stereoselective Tandem Bis-Electrophile Couplings of Diborylmethane
作者:Stephanie A. Murray、Michael Z. Liang、Simon J. Meek
DOI:10.1021/jacs.7b09309
日期:2017.10.11
[B(pin)]2-methane as a conjunctive reagent, resulting in the formation of two C-C bonds at a single carbon center bearing a C(sp3) organoboron functional group. Products are obtained in 42-99% yield, and up to >20:1 dr. The utility of the approach is highlighted by stereospecific transformations entailing allylation, tandem cross coupling, and application to the synthesis 1,3-polyol motifs.
renewable olefin β‐pinene with molecular oxygen was experimentally and computationally investigated. Peroxyl radicals abstract weakly bonded allylic hydrogen atoms from the substrate, yielding allylic hydroperoxides (i.e., myrtenyl and pinocarvyl hydroperoxide). In addition, peroxyl radicals add to the CC bond of the substrate to form an epoxide. It was found that a relatively high peroxyl radical concentration
作者:V. A. Startseva、A. V. Bodrov、A. V. Aref’ev、I. V. Kuznetsov、O. A. Lodochnikova、V. V. Klochkov、L. E. Nikitina
DOI:10.1007/s10600-014-1045-2
日期:2014.10
New bicyclic thioterpenoids with heterocyclic fragments were prepared via reactions of (–)-β-pinene and its oxide with 1-phenyl-1H-tetrazole-5-thiol, 1-methylimidazole-2-thiol, and 4,6-dimethyl-2-pyrimidinesulfenylchloride.