Novel Regio- and Stereoselective Cascade 6-endo-trig Cyclisations from Polyene Acyl Radical Intermediates Leading to Steroid-Like Pentacycles and Heptacycles
摘要:
In a quite remarkable regio- and stereoselective manner, each of the (all-E)-polyene selenoates 5a-c is shown to undergo cascade radical-mediated polycyclisations via consecutive 6-endo-trig reactions, leading to the corresponding all-trans, anti, tri-, penta- and heptacycles, i.e., 20, 23, and 25, in good yields. The configurations of these 'steroid-like' polycycles followed from detailed examination and correlation of chemical shift data in their C-13-NMR spectra.
Synthesis of lurlene, the sex pheromone of the green flagellate Chlamydomonas allensworthii
摘要:
Lurlene [(4E,8E,12E)-14-[2'-hydroxy-3',4'-dimethyl-5'-(1 ''-beta-D-xylopyranosyloxy)phenyl]-4,8,12-trimethyltetradeca-4,8,12-trienoic acid, 1], the sex pheromone produced by the female gametes of Chlamydomonas allensworthii, was synthesized as a mixture of 1 and its (12Z)-isomer, and the mixture was bioactive.
A Strategy for Position-Selective Epoxidation of Polyprenols
作者:Vijay Gnanadesikan、E. J. Corey
DOI:10.1021/ja801899v
日期:2008.6.1
developed for the efficient site-selective epoxidation of poylolefinic isoprenoid alcohols, based on the use of an internal control element for intramolecular reaction. The approach is illustrated by application to a series of polyisoprenoid alcohols (polyprenols) at substrate concentration of 0.5 mM. With polyprenol substrates having the hydroxyl function at one terminus, the internal epoxidation can be directed
基于使用内部控制元件进行分子内反应,已开发出一种有效的策略,用于聚烯烃类异戊二烯醇的有效位点选择性环氧化。该方法通过应用于一系列底物浓度为 0.5 mM 的聚异戊二烯醇(聚异戊二烯醇)来说明。对于在一个末端具有羟基官能团的聚异戊二烯醇底物,内部环氧化作用可针对聚异戊二烯醇的双键,该双键距末端羟基异戊二烯亚单元四或五处。
Biomimetic Cyclization of Epoxide Precursors of Indole Mono-, Sesqui- and Diterpene Alkaloids by Lewis Acids
Cyclization of the synthesized epoxide precursors of indole mono-, sesqui- and diterpene alkaloids was performed to elucidate the mechanism for biomimetic cationic cyclization to polycyclic structures. 3-(6,7-Epoxygeranyl)indole (11), 3-(10,11-epoxyfarnesyl)indole (2) and 3-(14,15-epoxygeranylgeranyl)indole (3) were respectively synthesized from geraniol, farnesol and geranylgeraniol in 6 or 7 steps
Combinatorial evolution of site- and enantioselective catalysts for polyene epoxidation
作者:Phillip A. Lichtor、Scott J. Miller
DOI:10.1038/nchem.1469
日期:2012.12
Selectivity in the catalytic functionalization of complex molecules is a major challenge in chemical synthesis. The problem is magnified when there are several possible stereochemical outcomes and when similar functional groups occur repeatedly within the same molecule. Selective polyene oxidation provides an archetypical example of this challenge. Historically, enzymatic catalysis has provided the only precedents. Although non-enzymatic catalysts that meet some of these challenges became known, a comprehensive solution has remained elusive. Here, we describe low molecular weight peptide-based catalysts, discovered through a combinatorial synthesis and screening protocol, that exhibit site- and enantioselective oxidation of certain positions of various isoprenols. This diversity-based approach, which exhibits features reminiscent of the directed evolution of enzymes, delivers catalysts that compare favourably to the state-of-the-art for the asymmetric oxidation of these compounds. Moreover, the approach culminated in catalysts that exhibit alternative-site selectivity in comparison to oxidation catalysts previously described. Aspartic acid-based catalysts that are selective for oxidation of either the 2,3 position or the 6,7 position of certain isoprenols have been discovered. The catalysts emerged from a diversity-based approach employing the one-bead-one-compound libraries. The site-selectivity of the catalysis seems to derive from the hydroxyl group in the substrate, although the details of this are not yet known.
[EN] BIOSYNTHESIS OF CHEMICALLY DIVERSIFIED NON-NATURAL TERPENE PRODUCTS<br/>[FR] BIOSYNTHÈSE DE PRODUITS TERPÉNIQUES NON NATURELS DIVERSIFIÉS CHIMIQUEMENT
申请人:UNIV MICHIGAN STATE
公开号:WO2021092200A1
公开(公告)日:2021-05-14
The disclosure relates to compounds of the formulae (l)-(IV) and their use as substrates for making terpenoids. New substrates for terpene biosynthesis and methods for making new types of terpenes are described herein. Diterpenes occupy a unique molecular space with critical pharmaceutical applications over a diverse spectrum including anti-microbial, anti-cancer, immunomodulatory and psychoactive properties.