Enzymatic resolution of the 1,3,3-trimethyl-2-oxabicyclo[2.2.2]octane (1,8-cineole) system
摘要:
Regioselective oxidation of 1,8-cineole 1 with chromyl acetate according to a literature procedure gave the bicyclic 2-ketocineole 8 as the major product along with the symmetrical diketocineole 9. The bicyclic monoketone was reduced with lithium aluminum hydride followed by exposure to acetyl chloride/DMAP to afford the exo-acetate (+/-)-4b. Pig liver esterase (PLE)-mediated hydrolysis of the racemic acetate provided the alcohol (-)-2b (45%) together with its antipodal acetate (+)-4b (43%) in greater than 99% enantiomeric purity, as determined by analysis of the Mosher's ester derivatives. Iodination of the alcohol exo-(+)-2b, obtained by hydrolysis of the resolved actetate with iodine/triphenylphosphine/imidazole, provided the corresponding endo iodide (-)-12a, which was easily dehydro halogenated with DBU under solvent-free conditions to provide the corresponding cineolene (-)-6 in an overall yield of 6 and 99%. e.e. (C) 2002 Elsevier Science Ltd. All rights reserved.
Experimental and theoretical insights into the formation of weak hydrogen bonds and H⋯H bonding interactions in the solid-state structure of two eucalyptol derivatives
作者:Carolina E. Galvez、Oscar E. Piro、Gustavo A. Echeverría、Norma Lis Robles、José O. G. Lezama、Sankaran Venkatachalam Sankaran、Subbiah Thamotharan、Margarita B. Villecco、María del H. Loandos、Diego M. Gil
DOI:10.1039/d2nj00428c
日期:——
C–H⋯O hydrogen bonds and H⋯H bondinginteractions. These interactions have also been described and studied energetically using DFT calculations. The nature and strength of these intermolecular contacts have been rationalized by using several computational tools including molecular electrostatic potential (MEP) surfaces, natural bondorbital analysis (NBO), Bader's theory of atoms in molecules (QTAIM)
(S)-(+)-O-methylmandelate esters of trans- and cis-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-5- and 6-ols (2- and 3-hydroxy-1,8-cineoles) were prepared, and eight diastereomers were separated. The absolute configuration of the asymmetric carbons of the cineole moiety of each diastereomer was determined by H-1 NMR data according to the Mosher theory. Each mandelate was reduced with LiAlHe4 to obtain optically pure hydroxy-1,8-cineoles, this being followed by acetylation to afford optically pure acetoxy-1,8-cineoles. These acetates were subjected to chiral GC, using a cyclodextrin column, and the enantiomeric purity of trans- and cis-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-5- and 6-yl acetates in the aroma concentrate from the rhizomes of Alpinia galanga was determined as 93.9 (5S), 19.4 (5R), 63.5 (6R), and 100 (6R) % cc, respectively. The aroma character of each enantiomer was also evaluated by GC-sniffing.
Regiospecific functionalization of the monoterpene ether 1,3,3-trimethyl-2-oxabicyclo[2.2.2]octane (1,8-cineole). Synthesis of the useful bridged .gamma.-lactone 1,3-dimethyl-2-oxabicyclo[2.2.2]octan-3 .fwdarw. 5-olide
作者:Margarita V. De Boggiatto、Carola S. De Heluani、Ines J. S. De Fenik、Cesar A. N. Catalan
DOI:10.1021/jo00384a023
日期:1987.4
Enzymatic resolution of the 1,3,3-trimethyl-2-oxabicyclo[2.2.2]octane (1,8-cineole) system
作者:Frederick A. Luzzio、Damien Y. Duveau
DOI:10.1016/s0957-4166(02)00313-0
日期:2002.6
Regioselective oxidation of 1,8-cineole 1 with chromyl acetate according to a literature procedure gave the bicyclic 2-ketocineole 8 as the major product along with the symmetrical diketocineole 9. The bicyclic monoketone was reduced with lithium aluminum hydride followed by exposure to acetyl chloride/DMAP to afford the exo-acetate (+/-)-4b. Pig liver esterase (PLE)-mediated hydrolysis of the racemic acetate provided the alcohol (-)-2b (45%) together with its antipodal acetate (+)-4b (43%) in greater than 99% enantiomeric purity, as determined by analysis of the Mosher's ester derivatives. Iodination of the alcohol exo-(+)-2b, obtained by hydrolysis of the resolved actetate with iodine/triphenylphosphine/imidazole, provided the corresponding endo iodide (-)-12a, which was easily dehydro halogenated with DBU under solvent-free conditions to provide the corresponding cineolene (-)-6 in an overall yield of 6 and 99%. e.e. (C) 2002 Elsevier Science Ltd. All rights reserved.
Herbicidal Activity of Cineole Derivatives
作者:Allan F. M. Barton、Bernard Dell、Allan R. Knight
DOI:10.1021/jf101827v
日期:2010.9.22
dose-dependent herbicidalactivity against annual ryegrass and radish with many of the derivatives showing improved herbicidalactivityrelative to 1,8-cineole and high-cineole eucalyptus oil. Increased activity of cineole ester derivatives compared to their associated hydroxy-cineole and carboxylic acid was not observed. No relationship between lipophilicity of the carboxylic acid portion of cineole ester derivatives
精油及其成分具有作为生态可接受的农药的潜力,也可能具有新颖的作用方式。在这项工作中,制备了大多数桉树油中主要成分天然单萜1,8-cineole 3和1,4-cineole 4的羟基和酯衍生物,并针对一年生黑麦草(黑麦草)进行了芽前除草活性。和萝卜(萝卜)变种 Long Scarlet(Long Scarlet)在基于实验室的生物测定法中进行了研究。1,8-桉树脑,桉树油和所有衍生物对一年生黑麦草和萝卜均表现出剂量依赖性的除草活性,其中许多衍生物相对于1,8-桉树脑和高桉树脑的桉树油具有更好的除草活性。与它们相关的羟基-桉树脑和羧酸相比,未观察到桉树脑酯衍生物的活性增加。没有观察到桉树脑酯衍生物的羧酸部分的亲脂性与除草活性之间的关系。结果表明这些桉树脑衍生物可能是环境可接受的除草剂。