930649-65-3Relevant academic research and scientific papers
A general strategy for the stereoselective synthesis of the furanosesquiterpenes structurally related to pallescensins 1-2
Serra, Stefano
, (2019/05/24)
Here, we describe a general stereoselective synthesis of the marine furanosesquiterpenes structurally related to pallescensins 1-2. The stereoisomeric forms of the pallescensin 1, pallescensin 2, and dihydropallescensin 2 were obtained in high chemical and isomeric purity, whereas isomicrocionin-3 was synthesized for the first time. The sesquiterpene framework was built up by means of the coupling of the C10 cyclogeranyl moiety with the C5 3-(methylene)furan moiety. The key steps of our synthetic procedure are the stereoselective synthesis of four cyclogeraniol isomers, their conversion into the corresponding cyclogeranylsulfonylbenzene derivatives, their alkylation with 3-(chloromethyl)furan, and the final reductive cleavage of the phenylsulfonyl functional group to afford the whole sesquiterpene framework. The enantioselective synthesis of the α-, 3,4-dehydro-γ- and γ-cyclogeraniol isomers was performed using both a lipase-mediated resolution procedure and different regioselective chemical transformations.
Preparation of (S)-γ-cyclogeraniol by lipase-catalyzed transesterification and synthesis of (+)-trixagol and (+)-luffarin-P
Fujii, Mikio,Morimoto, Yosuke,Ono, Machiko,Akita, Hiroyuki
, p. 160 - 166 (2015/12/04)
Lipase-catalyzed kinetic resolution of γ-cyclogeraniol by Candida antarctica lipase B yielded 23% of enantiomerically pure (S)-γ-cyclogeraniol. (+)-trixagol and (+)-luffarin-P were synthesized from the obtained (S)-γ-cyclogeraniol, and the absolute config
Acid-catalyzed cyclization of terpenes under homogeneous and heterogeneous conditions as probed through stereoisotopic studies: A concerted process with competing preorganized chair and boat transition states
Raptis, Christos,Lykakis, Ioannis N.,Tsangarakis, Constantinos,Stratakis, Manolis
scheme or table, p. 11918 - 11927 (2010/04/28)
Based on stereoisotopic studies and β-secondary isotope effects, we propose that the acid-catalyzed cyclization of geranyl acetate proceeds through a concerted mechanism. Under heterogeneous conditions (zeolite Y confinement), a preorganized chairlike transition state predominates, whereas under homogeneous conditions the boat-and chairlike transition states are almost isoenergetic. For the case of farnesyl acetate, we propose that under homogeneous conditions a concerted dicyclization occurs with a preorganized boat-chair transition state competing with the chair-chair transition state. Under zeolite confinement conditions, the chair-chairlike dicyclization transition state is highly favorable. The preference of chairlike transition states within the cavities of zeolite Y is attributed to a transition state shape selectivity effect.
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.
