Structures, Biological Activities, and Total Syntheses of 13-Hydroxy- and 13-Acetoxy-14-nordehydrocacalohastine, Novel Modified Furanoeremophilane-Type Sesquiterpenes from <i>Trichilia cuneata</i>
13-Hydroxy-14-nordehydrocacalohastine (2) and 13-acetoxy-14-nordehydrocacalohastine (3), two novel modified furanoeremophilane-type sesquiterpenes isolated from Trichilia cuneata, showed inhibitory activities for membrane lipid peroxidation in mitochondria and microsomes. The first, highly convergent totalsyntheses of new compounds 2 and 3 have also been achieved via a palladium-mediated three-component
Simultaneous Synthesis of Both Rings of Chromenes via a Benzannulation/<i>o</i>-Quinone Methide Formation/Electrocyclization Cascade
作者:Nilanjana Majumdar、Keith A. Korthals、William D. Wulff
DOI:10.1021/ja210655g
日期:2012.1.18
A new route to the chromene ring system has been developed which involves the reaction of an α,β-unsaturated Fischer carbenecomplex of chromium with a propargyl ether bearing an alkenyl group on the propargylic carbon. This transformation involves a cascade of reactions that begins with a benzannulation reaction and is followed by the formation of an o-quinone methide, and finally results in the emergence
开发了一种色烯环体系的新路线,该路线涉及铬的α,β-不饱和费歇尔卡宾络合物与在炔丙碳上带有烯基的炔丙醚的反应。这种转化涉及一系列反应,从苯并环化反应开始,然后形成邻醌甲基化物,最后在电环化时产生色烯。通过使用芳基卡宾络合物,该反应被扩展以提供通路。这是色烯的首次合成,其中色烯系统的两个环均在一步中生成,并在 lapachenole 和维生素 E 的合成中得到突出体现。
Rhodium-Catalyzed Intra- and Intermolecular [5 + 2] Cycloaddition of 3-Acyloxy-1,4-enyne and Alkyne with Concomitant 1,2-Acyloxy Migration
作者:Xing-Zhong Shu、Xiaoxun Li、Dongxu Shu、Suyu Huang、Casi M. Schienebeck、Xin Zhou、Patrick J. Robichaux、Weiping Tang
DOI:10.1021/ja2109097
日期:2012.3.21
type of rhodium-catalyzed [5 + 2] cycloaddition was developed for the synthesis of seven-membered rings with diverse functionalities. The ring formation was accompanied by a 1,2-acyloxy migration event. The five- and two-carbon components of the cycloaddition are 3-acyloxy-1,4-enynes (ACEs) and alkynes, respectively. Cationic rhodium(I) catalysts worked most efficiently for the intramolecular cycloaddition
Unlocking Acyclic π-Bond Rich Structure Space with Tetraethynylethylene–Tetravinylethylene Hybrids
作者:Kelsey L. Horvath、Nicholas L. Magann、Madison J. Sowden、Michael G. Gardiner、Michael S. Sherburn
DOI:10.1021/jacs.9b08885
日期:2019.12.18
Literature reports describe tetraethynylethylene (TEE) as unstable but tetravinylethylene (TVE) as stable. The stabilities of these two known compounds are reinvestigated, along with those of five unprecedented TEE-TVE hybrid compounds. The five new C10 hydro-carbons possess a core, tetrasubstituted C=C bond carrying all possible combinations of vinyl and ethynyl groups. A unified strategy is described
Olefin Cross-Metathesis as a Tool in Natural Product Degradation. The Stereochemistry of (+)-Falcarindiol
作者:Anokha S. Ratnayake、Thomas Hemscheidt
DOI:10.1021/ol027033z
日期:2002.12.1
olefin cross-metathesis using Grubbs' second generation catalyst and ethylene gas to degrade falcarindiol to the symmetrical 1,9-decadiene-4,6-diyne-3,8-diol. The reaction is completely selective for net removal of the aliphatic side chain. Degradation of (+)-falcarindiol from Tetraplasandra hawaiiensis yields a meso product as shown by chiral HPLC. Hence, (+)-falcarindiol from this source has a (3R,8S)-configuration