An Unusual Example of a 6-Endo-Dig Addition to an Unactivated Carbon-Carbon Triple Bond
摘要:
Methyl 2-[2-[2-(1-hydroxy-1-ethyl)phenyl]ethynyl]benzoate was prepared as an intermediate for subsequent conversion to an a-diazo ketone. Under the basic conditions used to hydrolyze the methyl ester, the neighboring hydroxyl functionality underwent reaction with the unactivated acetylenic group, producing a benzopyranyl-substituted alpha-diazoacetophenone. Treatment of this diazocarbonyl compound with a catalytic quantity of rhodium(II) mandelate afforded a novel dibenzo[a,e]cyclononenone derivative. The reaction proceeds via an initially formed oxonium ylide which rearranges further by means of a 1,2-alkyl shift. A prime factor in determining the direction of internal cyclization to the triple bond is the presence of the carbomethoxy group in the ortho position of the beta-phenyl ring. Thus, in contrast with related systems which exhibit a clear preference for 5-exo-dig cyclization at the acetylenic center, the 6-endo-dig addition is the preferred pathway for the o-formyl- and o-carbomethoxy-substituted alkynyl alcohols. Careful monitoring of the reaction actually showed that the reaction proceeds by initial formation of the 5-exo-dig product followed by a novel rearrangement to the 6-endo product.
Synthesis of dibenzocyclohepta[1,2-<i>a</i>]naphthalene derivatives from phenylacetaldehyde and alkynyl benzyl alcohols <i>via</i> sequential electrophilic addition and double Friedel–Crafts reactions
作者:Archana K. Sahu、Ramanjaneyulu Unnava、Bipin K. Behera、Anil K. Saikia
DOI:10.1039/d1ob00057h
日期:——
been developed for the synthesis of substituted 9H-dibenzo[3,4:6,7]-cyclohepta[1,2-a]naphthalenes from phenylacetaldehydes and ortho-alkynyl benzyl alcohols in the presence of a Lewis acid in moderate to good yields within a short reaction time. Interestingly, the reaction proceeds through a highly regioselective electrophilic addition followed by double Friedel–Crafts reaction to form uncommon dibenzo-fused
已经开发了一种简单的方法,用于在路易斯酸存在下,由苯乙醛和邻炔基苄基醇合成取代的9 H-二苯并[3,4:6,7]-环庚[1,2- a ]萘。在较短的反应时间内中度到良好的收率。有趣的是,该反应是通过高度区域选择性的亲电加成反应进行的,然后进行两次Friedel-Crafts反应,形成不常见的二苯并稠合的七元碳环。
Regioselective synthesis of phthalans via Cu(OTf)2-catalyzed 5-exo-dig intramolecular hydroalkoxylation of 2-(ethynyl)benzyl alcohols
efficient, regioselective Cu(OTf)2-catalyzed 5-exo-dig intramolecular hydroalkoxylation of 2-(ethynyl)benzyl alcohol, which provides a concise access to functionalized phthalan in high yields has been developed. A wide range of substrates possessing terminal, internal, and heteroaromatic alkynes can be efficiently transformed into the targeted phthalans. Substrates with primary, secondary, and tertiary benzyl
Regioselective synthesis and evaluation of 3-alkylidene-1, 3-dihydroisobenzofurans as potential antidepressant agents
作者:C PRAVEEN、C IYYAPPAN、K GIRIJA、K SURESH KUMAR、P T PERUMAL
DOI:10.1007/s12039-011-0150-z
日期:2012.3
3-Alkylidene-1,3-dihydroisobenzofurans exhibited moderate antidepressant activity as evaluated by forced swim and tail suspension test methods. Virtual screening was carried out by docking the designed compounds into the serotonin binding sites of arabinase protein to predict the analogue binding mode of the compounds to the SSRIs.
Synthesis of 2-Aryl Acetophenones via Hydrobromination and Oxy-isomerization of (<i>o</i>-Arylethynyl)benzyl Alcohols
作者:Tzu-Hsuan Kuan、Duen-Ren Hou
DOI:10.1021/acs.joc.1c00294
日期:2021.5.7
Hydrobromination and oxy-isomerization of (o-arylethynyl)benzyl alcohols to yield brominated aryl ketones were achieved with bromotrimethylsilane. The substrate scope suggested that vinyl carbocations, stabilized by the conjugated aryl groups, are the reaction intermediates. 1H-Isochromene was also detected by 1H NMR, and an isolated 1H-isochromene was converted to the product when retreated with TMSBr
用溴代三甲基硅烷实现了(邻-芳基乙炔基)苄醇的氢溴化和氧异构化,生成溴化的芳基酮。底物范围表明,通过共轭芳基稳定的乙烯基碳阳离子是反应中间体。还通过1 H NMR检测到1 H-异戊二烯,当用TMSBr处理时,分离出的1 H-异戊二烯转化为产物。1 H-异戊二烯的形成等同于6-内挖-环化,并与在基本条件下的相应反应形成对比,在该条件下,以5-外-挖为主导。
Selective cyclization of alkynols and alkynylamines catalyzed by potassium tert-butoxide
作者:Deng Yuan Li、Ke Ji Shi、Xiao Feng Mao、Zheng Le Zhao、Xin Yan Wu、Pei Nian Liu