Stereochemical disposition of the geminal dimethyl groups in the enzymatic cyclization of geranyl diphosphate to (+)-bornyl diphosphate by recombinant (+)-bornyl diphosphate synthase from Salvia officinalis
作者:Mitchell L Wise、Hyung-Jung Pyun、Greg Helms、Bryce Assink、Robert M Coates、Rodney B Croteau
DOI:10.1016/s0040-4020(01)00451-3
日期:2001.6
Regiospecifically deuterated geranyl diphosphate, in concert with NMR spectrometry, was employed to demonstrate that the trans-methyl group (C8) of geranyl diphosphate becomes the C9 carbon of (+)-bornyl diphosphate (geminal methyl syn to the diphosphate moiety) and that the cis-methyl group (C9) becomes the C8 (geminal methyl anti to the diphosphate). The syntheses of the relevant substrates and products, with accompanying spectrometric data are provided. (C) 2001 Elsevier Science Ltd. All rights reserved.
Syn Stereochemistry of Cyclic Ether Formation in 1,8-Cineole Biosynthesis Catalyzed by Recombinant Synthase from <i>Salvia officinalis</i>
作者:Mitchell L. Wise、Marek Urbansky、Gregory L. Helms、Robert M. Coates、Rodney Croteau
DOI:10.1021/ja0265714
日期:2002.7.1
Regiospecifically labeled geranyl diphosphates ((2E,6E)-[1,1,8,8,8-(2)H(5)]- and (2E,6Z)-[1,1,9,9,9-(2)H(5)]-GDP) and D(2)O incorporation, in concert with NMR spectrometry, were employed to demonstrate a unique intramolecular syn-facial protonation-cyclization mechanism of action of 1,8-cineole synthase.
Stereochemistry of Formation of theβ-Ring of Lycopene: Biosynthesis of (1R,1′R)-β,β-[16,16,16,16′,16′,16′-2H6]Carotene from [16,16,16,16′,16′,16′-2H6]Lycopene inFlavobacterium R 1560
作者:Sasank Sekhar Mohanty、Peter Uebelhart、Conrad Hans Eugster
measurements on the isolated β,β-carotene, allowing its centers of chirality to be assigned as (1S,1′S). iv) The same chirality resulted from incorporation of [2H3]mevalonate into zeaxanthin. The syntheses of specifically deuteriated [2H3]GPP, [2H3]FPP, and [2H3]GG are described.
Stereoselective Disposition of the Geminal Dimethyl Group in the Cyclization of Geranyl Acetate under Zeolite Confinement Conditions
作者:Constantinos Tsangarakis、Manolis Stratakis
DOI:10.1002/ejoc.200600367
日期:2006.10
The stereochemistry in the acid-catalysed biomimetic cyclization of [8,8,8-D3]geranyl acetate was examined in solution and under conditions of zeolite Y confinement. In the intrazeolite reaction the gem-allylic methyl group adopts a diastereoselective disposition in the cyclization product (64 % dr). In contrast, the gem-dimethyl disposition in a homogeneous medium (ClSO3H/2-nitropropane) proceeds