72445-03-5Relevant academic research and scientific papers
Lipase-mediated resolution of the hydroxy-cyclogeraniol isomers: application to the synthesis of the enantiomers of karahana lactone, karahana ether, crocusatin C and γ-cyclogeraniol
Serra, Stefano,Gatti, Francesco G.,Fuganti, Claudio
experimental part, p. 1319 - 1329 (2009/12/01)
A comprehensive study on the lipase PS-mediated resolution of different hydroxy-geraniol isomers is reported. A number of α-, β- and γ-isomers bearing a 2-, 3- or 4-hydroxy functional group were synthesised regioselectively and then submitted to the lipase-mediated kinetic acetylation. The latter experiments showed that the 2-hydroxy isomers 4, 5 and 14 (α, γ and β, respectively) as well as cis-3-hydroxy α-cyclogeraniol 7 and cis-4-hydroxy γ-cyclogeraniol 10 could be easily resolved by this procedure. The enantiomeric purity of the main part of these compounds was increased by recrystallisation and the enantiopure diols obtained were used as building blocks for the synthesis of the natural terpenoids karahana lactone, karahana ether and crocusatin C and for the preparation of the synthetic intermediate γ-cyclogeraniol. The absolute configurations of the enantiomers of the diols 7, 10, 14 and 19 were determined by chemical correlation with the known compounds 40, 41, 39 and 41, respectively.
Zeolite NaY-promoted monocyclization of epoxy polyene terpenes: A unique route for the direct synthesis of incompletely cyclized naturally occurring terpenols
Tsangarakis, Constantinos,Raptis, Christos,Arkoudis, Elias,Stratakis, Manolis
scheme or table, p. 1587 - 1600 (2009/07/30)
A variety of epoxy polyene terpenes cyclize readily by confinement within zeolite NaY to form primarily products of monocyclization. The monocyclization pathway is highly predominant, irrespectively of the side chain of the epoxy terpene, while the monocyclic products possess regioselectively an exomethylenic double bond. The selective monocyclization in the case of epoxyfarnesyl acetate, epoxyfarnesylacetone or 2,3-epoxysqualene, provides a direct route to the synthesis of a variety of natural products, such as elengasidiol, farnesiferols B-D, achilleol A, camelliol C and to four farnesylacetone-derived metabolites isolated from the brown algae Cystophora monoliformis. The optical rotation of achilleol A derived from the cyclization of (S)-2,3-epoxysqualene matches with that of the natural product, thus the absolute configuration of achilleol A was established as 1S,3R. From the mechanistic point of view, the NaY-promoted cyclization of 9,10-epoxygeranylacetone, selectively deuterium labelled at the C-10 methyl group, is >97% stereoselective with respect to the topicity of the gem-dimethyl group. This result is in agreement with a concerted mechanism. Finally, we have proved through labelling experiments, for the first time, that the biomimetic transformation of epoxy polyene terpenes to 2,3,4-trimethylcyclohexanones upon acid catalysis is a highly stereoselective process. Thus, the less hindered gem-methyl group on the epoxide functionality becomes α- to the carbonyl in the final isomerized product.
Selective monocyclization of epoxy terpenoids promoted by zeolite NaY. A short biomimetic synthesis of elegansidiol and farnesiferols B-D
Tsangarakis, Constantinos,Arkoudis, Elias,Raptis, Christos,Stratakis, Manolis
, p. 583 - 586 (2008/02/02)
Epoxy terpenes cyclize readily, by confinement within zeolite NaY, to form exomethylenic cyclohexanols as the major products. The selective monocyclization of 10,11-epoxyfarnesyl acetate within NaY provides a short and efficient biomimetic route to (±)-elengasidiol and (±)-farnesiferols B-D.
Synthesis of (+/-)-Karahana Ether and Karahanaenone by Selective Cyclization of 6,7-Epoxygeranyl Acetate
Barrero, Alejandro F.,Alvarez-Manzaneda, Enrique J.,Palomino, P. Linares
, p. 13239 - 13250 (2007/10/02)
Efficient methods for preparing (+/-)-karahana ether (1b) and karahanaenone (2) from 6,7-epoxygeranyl acetate (3), by Lewis-acid-catalyzed electrophilic cyclization, are described.
Synthesis of (+/-)-karahana ether and a (+/-)-labdadienoic acid by the electrophilic cyclization of epoxy allylsilanes
Armstrong, Rosemary J.,Weiler, Larry
, p. 584 - 596 (2007/10/02)
The epoxy allylsilanes 7 and 16 were synthesized by stereoselective routes from β-keto esters and cyclized with Lewis acids in good yield.The monocyclic product from 7 was converted into (+/-)-karahana ether (10), and the bicyclic product from 20 was used in a synthesis of the 3-hydroxylabdadienoic acid 24b.
Stereoselective cyclization of epoxy allylsilanes. A synthesis of karahana ether
Armstrong, Rosemary J.,Weiler, Larry
, p. 214 - 216 (2007/10/02)
Epoxy allylsilanes can be cyclized with Lewis acids to give cyclic alcohols in a biomimetic synthesis of mono and bicyclic compounds.The allylsilane has a pronounced effect on activating an olefin in this cyclization and producing the exocyclic methylene
