Expedient Syntheses of β-Iodofurans by 5-endo-dig Cyclisations
作者:Sean P. Bew、Gamila M. M. El-Taeb、Simon Jones、David W. Knight、Wen-Fei Tan
DOI:10.1002/ejoc.200700681
日期:2007.12
yields of the corresponding β-iodofurans. The necessary precursors are available from a number of different approaches, notably regioselective bis-hydroxylation of conjugated enynes and the addition of acetylides to α-hydroxy carbonyl groups. The initial iodofurans can be homologated using a number of strategies, ranging from various transition metal-catalysed couplings to halogen-metal exchange and subsequent
Nickel-Catalyzed Intermolecular [2 + 2] Cycloaddition of Conjugated Enynes with Alkenes
作者:Akira Nishimura、Masato Ohashi、Sensuke Ogoshi
DOI:10.1021/ja3074775
日期:2012.9.26
A nickel-catalyzed intermolecular [2 + 2] cycloaddition of conjugated enynes with alkenes has been developed. A variety of electron-deficient alkenes as well as electronically neutral norbornene and 1-decene were applicable to this reaction. The use of conjugated enynes circumvented possible side rections, such as oligomerizations and cyclotrimerizations. The isolation of reaction intermediate complexes
Integrated Chemical Process. One-Pot Preparation of Acetylenes by Peterson-Sulfone Elimination
作者:Akihiro Orita、Naonori Yoshioka、Junzo Otera
DOI:10.1246/cl.1997.1023
日期:1997.10
Integration of silylation of α-sulfonyl carbanion, addition of the anion of the resulting α-silyl sulfone to aldehyde, Peterson elimination, and sulfone elimination leads to one-pot synthesis of acetylenes.
Synthesis of α-Hydroxyallenes by Copper-Catalyzed S<sub>N</sub>2′ Substitution of Propargylic Dioxolanones
作者:Xiaoping Tang、Simon Woodward、Norbert Krause
DOI:10.1002/ejoc.200900226
日期:2009.6
catalytic method for the synthesis of α-hydroxyallenes is described. Efficient SN2′ substitution of propargylic dioxolanones has been achieved with a copper(I)/P(OBu)3 catalyst using Grignardreagents as the nucleophiles. The reaction tolerates a wide variety of propargylic dioxolanones, the corresponding primary and secondary α-hydroxyallenes are obtained in good to excellent yields and excellent diastereoselectivity
Through the use of [PdCl(C3H5)]2/cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as catalyst, a range of vinylbromides undergoes Sonogashira cross-coupling reaction with a variety of alkynes, leading to the corresponding 1,3-enynes in good yields. The reaction tolerates several alkynes such as phenylacetylene, dec-1-yne, 2-methylbut-1-en-3-yne a range of alk-1-ynols, 3,3-diethoxyprop-1-yne
通过使用[PdCl(C 3 H 5)] 2 /顺式,顺式,顺式-1,2,3,4-四(二苯基膦甲基)环戊烷作为催化剂,一定范围的乙烯基溴与各种炔烃进行Sonogashira交叉偶联反应,从而以高收率得到相应的1,3-烯炔。该反应可耐受几种炔烃,例如苯乙炔,癸-1-炔,2-甲基丁-1-烯-3-炔,一系列烷-1-炔醇,3,3-二乙氧基丙-1-炔和炔丙基胺。在苯乙炔,dec-1-yne,but-3-yn-1-ol,pent-4-yn-1-ol,3,3-dithoxyprop-1-yne或1,1存在下观察到更高的反应速率-二丙基-2-丙炔胺比与炔丙醇,3-甲氧基-丙-1-炔或2-甲基丁-1-烯-3-炔。该催化剂即使在空间受阻的乙烯基溴化物如溴代三苯基乙烯或2-溴-3-甲基-丁-2-烯的反应中也可以低负荷使用。