Total synthesis of brevenal

The convergent total synthesis of brevenal, a non-toxic brevetoxin antagonist, has been achieved. The ABC ring segment and the E ring precursor were connected by the intramolecular allylation followed by ring-closing metathesis to furnish the pentacyclic ether compound. An alternative route to the key synthetic intermediate, a pentacyclic ether core, was also examined. The right- and left-hand side chains were introduced by Wittig and Horner-Wadsworth-Emmons reactions, respectively, to furnish brevenal (1).     

Pheromone synthesis. Part 244: Synthesis of the racemate and enantiomers of (11Z,19Z)-CH503 (3-acetoxy-11,19-octacosadien-1-ol), a new sex pheromone of male Drosophila melanogaster to show its (S)-isomer and racemate as bioactive

The enantiomers of (11Z,19Z)-3-acetoxy-11,19-octacosadien-1-ol were synthesized from the enantiomers of 3,4-epoxy-1-butanol PMB ether. Its racemate was also synthesized. Its (S)-isomer and racemate were shown to possess the same pheromone activity as CH503, a long-lived inhibitor of male courtship in Drosophila melanogaster, although the racemate was less active.     

Development of predictive quantitative retention–activity relationship models of alkaloids by mixed micellar liquid chromatography

The mixed micellar liquid chromatography is a mode that uses mixed micellar system of Brij35/SDS (85 : 15) as a mobile phase under adequate experimental conditions, can simulate the resting membrane potential and the conformation of the long hydrophilic polyoxyethylene chains remains unchanged. In this article, the applications of biopartitioning micellar chromatography, using mixed micellar system to describe and estimate bioactivities of alkaloids, has been focused. The BMC_Brij35/SDS‐QRAR models of half‐life time, volume of distribution, plasma clearance and area under concentration–time curve were obtained using Brij35‐SDS retention data. The aim is to take a look at the capability of the mixed micellar liquid chromatography model to describe and/or estimate the bioactivity of alkaloids. Copyright © 2009 John Wiley & Sons, Ltd.     

Lewis acid promoted aldol reaction of fluorinated silyl enol ethers from new fluoroacetylsilane derivatives

New fluorinated silyl enol ethers with various trialkylsilyl groups were synthesized. Various fluorinated β-hydroxy ketones were synthesized by Lewis acid promoted aldol reaction of silyl enol ethers with diverse aldehydes. Reactivity of various trialkylsilyloxy groups toward Lewis acid was also studied.     

Sulfamic acid as a cost-effective catalyst instead of metal-containing acids for acetolysis of cyclic ethers

Sulfamic acid has been used as an efficient catalyst and green alternative for metal-containing acidic materials to promote the acetolysis reaction of THF to produce 1,4-diacetoxybutane. This method is also applicable to the acetolysis of other cyclic ethers, such as methyl substituted THF and tetrahydropyran and 1,4-dioxane, which is less reactive.     

Novel branched ether formation via conjugate reduction of an unsaturated cyanohydrin derivative and its synthetic application to the EF-ring segment of ciguatoxin

A synthetic method for a branched ether system was developed. The method was based on Lewis-acid-promoted γ-position selective reduction of a γ-alkoxy β,γ-unsaturated α-silyloxy nitrile, prepared through a process including intermolecular hetero-Michael reaction of a 2-butynoate ester derivative with an alcohol. The method was efficiently applied to the synthesis of fused medium-ring ethers involving the EF-ring segment (2) of ciguatoxin (1).     

Guaiacol transprotection: replacement of the phenoxy isopropyl protecting function by acetyl

A one-step method for the conversion of isopropyl protected guaiacols to the corresponding acetates is reported. Treating 6-substituted isopropyl protected guaiacols with trimethylsilyl trifluoromethanesulfonate in a mixture of acetic anhydride and acetonitrile affords 6-substituted guaiacol acetates in yields ranging from 35% to 99%.     

Double benzyne-furan cycloaddition and the assembly of 1,1-binaphthyl and 1,1-dinaphthyl ether systems

1,1^′-Binaphthyl and 1,1^′-dinaphthyl ether systems have been prepared via double benzyne-furan cycloadditions, and a dibenzofuran derivative was formed as a major product in the lithiation of two di-(chloroaryl) ethers.     

含硫醚结构聚醚醚酮酮共聚物的非等温结晶动力学

聚芳醚酮类特种工程塑料由于其优异的机械性能、热稳定性、耐溶剂、耐辐照等特性而在航空航天、军事、电子、信息和核能等领域得到广泛的应用,为了得到使用温度更高的聚芳醚酮材料,人们开发了许多聚芳醚酮的新品种,但采用通常方法在提高材料使用温度的同时,材料的加工温度也越来越高,为了在不提高加工温度的前提下提高聚芳醚酮类材料的使用温度,我们已经成功地在聚醚醚酮的主链中引入可交联的硫醚结构,得到使用温度更高的可交联聚醚醚酮材料。     

一种新型磺化聚醚醚酮的合成、表征和性能

以特丁基对苯二酚、3,3′-二磺酸钠基-4,4′-二氟二苯酮和4,4′-二氟二苯酮为单体,制备了具有高磺化度的聚醚醚酮.该系列聚合物可溶,并具有良好的成膜性.对聚合物及其膜的一些性能进行了研究.