The Diels-Alder reaction, which is a traditional [4 + 2] cycloaddition with two carbon-carbon bond formations, is one of the most powerful tools to synthesize versatile and unique six-membered rings. We show that chiral supramolecular U-shaped boron Lewisacid catalysts promote the unprecedented multiselective Diels-Alder reaction of propargyl aldehyde with cyclic dienes. Independent from the substrate
Diels-Alder 反应是一种传统的 [4 + 2] 环加成反应,具有两个碳-碳键形成,是合成通用且独特的六元环的最强大工具之一。我们表明手性超分子 U 形硼路易斯酸催化剂促进了炔丙醛与环二烯前所未有的多选择性 Diels-Alder 反应。独立于底物控制,对映-、内/外-、π-面-、区域-、位点和底物选择性可以通过本 U 形催化剂进行控制。所得反应产物可用于手性二烯配体和(+)-沙霉素关键中间体的简明合成。这里介绍的结果可能部分有助于开发用于多选择性反应的人工酶样超分子催化剂,
General Synthetic Route to Substituted Bis(cyclopentadienyl)- and Bis(indenyl)methanes
作者:Ilya E. Nifant'ev、Pavel V. Ivchenko、Lyudmila G. Kus'mina、Yuri N. Luzikov、Alexander A. Sitnikov、Oleg E. Sizan
DOI:10.1055/s-1997-1200
日期:1997.4
Several substituted bis(cyclopentadienyl)- and bis(indenyl)methanes were synthesized directly from the corresponding cyclopentadienes (indenes) and ketones in KOH/DME two-phase mixture.
The development of a short synthetic approach to [small alpha]-thujone enabled the first syntheses of its main metabolites in an isotopically labelled form.
对小α-thujone的短合成方法的发展使得能够以同位素标记的形式首次合成其主要代谢产物。
Diastereoselective Synthesis of Dialkylated Bis(phosphino)ferrocenes: Their Use in Promoting Silver‐Mediated Nucleophilic Fluorination of Chloroquinolines
作者:Julien Roger、Sylviane Royer、Hélène Cattey、Aleksandr Savateev、Radomyr V. Smaliy、Aleksandr N. Kostyuk、Jean‐Cyrille Hierso
DOI:10.1002/ejic.201600502
日期:2017.1.10
and trimethylsilyl, has a significant influence on the stereoselectivity of the ensuing lithiation/phosphination reactions. Only the introduction of the tert-butyl groups ensures both a high yield and perfect diastereoselectivity, which leads to the exclusive formation of the rac planar chiral tert-butylated diphosphanes. The introduction of electron-rich and -poor phosphorus-based functional groups
报道了在膦基上带有芳基、烷基和杂环或多环取代基的二烷基化二茂铁基双(膦)的非对映选择性合成,以及它们在固态下的 X 射线结构分析和溶液中的多核 NMR 光谱表征. 在二茂铁主链上引入各种烷基,即叔丁基、异丙基和三甲基甲硅烷基,对随后的锂化/膦化反应的立体选择性有显着影响。只有引入叔丁基才能确保高产率和完美的非对映选择性,从而导致外消旋平面手性叔丁基化二膦的独家形成。引入富电子和贫磷基官能团,即呋喃基-、异丙基-、环己基-、苯基-、实现了间甲基膦基和苯并膦吲哚,并以中等至高产率得到新的烷基化二茂铁基二膦。进行了研究以将这些强大的烷基化二膦作为助剂应用于非常具有挑战性的钯催化的氯喹啉在 C-Cl 键上的亲核氟化。出乎意料的是,二茂铁基膦的显着有利影响是通过使用商业 AgF 试剂进行这种氟化而证明的,这使得任何钯添加都无用。因此,这种创新的亲核氟化避免了苛刻的条件(严格无水)和高度专业化的试剂。
Process for producing hinokitiol
申请人:Asahi Kasei Kabushiki Kaisha
公开号:US06310255B1
公开(公告)日:2001-10-30
A process for producing hinokitiol which comprises the step of obtaining 1-isopropylcyclopentadiene from cyclopentadiene and an isopropylating agent represented by the general formula R—X wherein R is an isopropyl group and X is a halogen or the like (first step), reacting it with a dihaloketene to obtain a ketene adduct (second step), and decomposing the ketene adduct (third step), said first step comprising the following three steps:
a) a preparation step of cyclopentadienyl metal;
b) a step of obtaining isopropylcyclopentadiene by isopropylating the cyclopentadienyl metal in an aprotic polar solvent; and
c) a step of isomerizing 5-isopropylcyclopentadiene in the product selectively to 1-isopropylcyclopentadiene with heat.