Assessing Synthetic Strategies: Total Syntheses of (±)-Neodolabellane-Type Diterpenoids
作者:Cory Valente、Michael G. Organ
DOI:10.1002/chem.200801161
日期:2008.9.19
Two strategies, namely a cross-metathesis/ring-closing metathesis and Pd-catalyzed Stille allylation/Nozaki-Hiyama-Kishi coupling, are examined for the preparation of neodolabellane-type diterpenoids 1 and 2. Whereas the first approach possessed synthetic limitations, the latter was successfully employed to provide compounds 1 and 2 in 8.8% (14 steps) and 8% (15 steps) overall yields, respectively
Desymmetrization of a Centrosymmetric Diepoxide: Efficient Synthesis of a Key Intermediate in a Total Synthesis of Hemibrevetoxin B
作者:Joanne M. Holland、Mark Lewis、Adam Nelson
DOI:10.1021/jo026456b
日期:2003.2.1
The preparation of an established intermediate in a totalsynthesis of hemibrevetoxinB is described. The acid-catalyzed cyclization of trans-4,5-epoxyoctane-2,7-dione exhibited a valuable mixture of kinetic and thermodynamic control: stereospecific epoxide opening was followed by equilibration of the products to provide the required trans-fused octahydropyrano[3,2-b]pyran ring system. Two-directional
of molecular symmetry can greatly improve the efficiency of syntheses. The symmetry embedded in the centrosymmetric AB dioxepane fragment of hemibrevetoxinB was exploited for the first time in the preparation of an established intermediate in its totalsynthesis. Desymmetrization of the centrosymmetric diepoxide 1 by enantioselective epoxide hydrolysis followed by acetonization gave the known synthetic
New Syntheses of 1,7-Dimethylnonyl Propanoate, the Western Corn Rootworm Pheromone, in Four Different Ways<i>via</i>Cross Metathesis, Alkylation and Coupling Reactions
作者:Kenji MORI
DOI:10.1271/bbb.90805
日期:2010.3.23
the four stereoisomers of 1,7-dimethylnonyl propanoate, the female sex pheromone of the western corn rootworm (Diabrotica virgifera virgifera LeConte), was synthesized in four different ways by employing one of the following four reactions as the key step: (i) crossmetathesis using the Grubbs I catalyst, (ii) crossmetathesis using the Grubbs II catalyst, (iii) alkylation of an alkynide anion, and
This invention relates to a process for dismuting functionalized olefins using a catalyst which has rhenium heptoxide on phosphated alumina and a metal hydrocarbon compound such as an alkyl tin. The olefins that may be dismuted are those which have a hetero atom such as oxygen, nitrogen or halide in the chain. Specific examples are olefinic compounds which have an ester, ether or a ketone group. The products of the reaction are useful chemical intermediates.