323178-42-3Relevant academic research and scientific papers
Stereochemistry of eudesmane cation formation during catalysis by aristolochene synthase from Penicillium roqueforti
Miller, David J.,Gao, Jiali,Truhlar, Donald G.,Young, Neil J.,Gonzalez, Veronica,Allemann, Rudolf K.
, p. 2346 - 2354 (2008)
The aristolochene synthase catalysed cyclisation of farnesyl diphosphate (1) has been postulated to proceed through (S)-germacrene A (3). However, the active site acid that reprotonates this neutral intermediate has so far proved difficult to identify and, based on high level ab initio molecular orbital and density functional theory calculations, a proton transfer mechanism has recently been proposed, in which proton transfer from C12 of germacryl cation to the C6,C7-double bond of germacryl cation (2) proceeds either directly or via a tightly bound water molecule. In this work, the stereochemistry of the elimination and protonation reactions was investigated by the analysis of the reaction products from incubation of 1 and of [12,12,12,13,13,13- 2H6]-farnesyl diphosphate (15) with aristolochene synthase from Penicillium roqueforti (PR-AS) in H2O and D2O. The results reveal proton loss from C12 during the reaction and incorporation of another proton from the solvent. Incubation of 1 with PR-AS in D2O led to the production of (6R)-[6-2H] aristolochene, indicating that protonation occurs from the face of the 10-membered germacrene ring opposite the isopropylidene group. Hence these results firmly exclude proton transfer from C12 to C6 of germacryl cation. We propose here Lys 206 as the general acid/base during PR-AS catalysis. This residue is part of a conserved network of hydrogen bonds, along which protons could be delivered from the solvent to the active site.
Superacid cyclization of (2E,6E,10E,14E)-8-phenylsulfonylgeranylfarnesol tetrahydropyranyl ether
Kulcitki,Grin'Ko,Barba,Ungur,Vlad
, p. 268 - 273 (2007)
A mixture of (13E,17E)-12-phenylsulfonylbicyclogeranylfarnesol tetrahydropyranyl ether (8) and (13E,17E)-12- phenylsulfonylbicyclogeranylfarnesol (9) was formed by superacid low-temperature cyclization of exclusively trans-8-phenylsulfonylgeranylfarnesol
Polyene cyclizations to indole diterpenes. The first synthesis of (+)-emindole SA using a biomimetic approach
Rainier,Smith III
, p. 9419 - 9423 (2007/10/03)
A biomimetic synthesis of the indole diterpene emindole SA (5) has been achieved via Lewis acid promoted polyene cyclization. (C) 2000 Elsevier Science Ltd.
