Efficient synthesis of tetra- and penta-substituted benzenes <i>via</i> a domino annulation reaction of a pyridinium ylide and chalcone <i>o</i>-enolate
作者:Feng-Shun Xu、Chen Yan、Jing Sun、Chao-Guo Yan
DOI:10.1039/d1nj03772b
日期:——
simple and highly efficient protocol for synthesizing tetra- and penta-substituted benzene derivatives has been developed. This synthesis was achieved by carrying out a tetramethylguanidine (TMD)-promoted reaction of 4-(N,N-dimethylamino)-1-phenacyl-pyridinium bromide with chalcone o-enolates in DMF at 100 °C. The reaction mechanism was believed to involve a sequential annulation reaction of pyridinium
已经开发了一种非常简单且高效的合成四和五取代苯衍生物的协议。该合成是通过在 DMF 中在 100°C下进行 4-( N , N-二甲氨基)-1-苯甲酰基-吡啶鎓与查尔酮邻烯醇盐的四甲基胍(TMD) 促进的反应来实现的。反应机理被认为涉及吡啶鎓叶立德的连续环化反应、最初形成的吡喃环的开环和芳构化过程。
Synthesis of Dispirocyclopentyl-3,3′-bisoxindoles via Domino Cycloaddition Reactions of 4-Dimethylaminopyridinium Bromides with 3-Phenacylideneoxindoles
作者:Lijuan Lu、Chaoguo Yan
DOI:10.1002/cjoc.201500438
日期:2015.10
The base mediated cycloadditionreactions of 4‐dimethylamino‐1‐phenacylpyridinium bromides with two molecular 3‐phenacylideneoxindoles in methylene dichloride afforded functionalized dispirocyclopentyl‐3,3′‐bisoxindoles in good yields and with high diastereoselectivity. The similar cycloadditionreactions of 1‐(N,N‐dialkylcarbamoylmethyl) and 1‐cyanomethyl 4‐dimethylamino‐pyridinium bromide in refluxing
在二氯甲烷中由碱介导的4-二甲氨基-1-苯并吡啶鎓溴化物与两个分子3-苯并亚苄基吲哚的环加成反应提供了高收率和高非对映选择性的功能化二螺环戊基-3,3'-双氧吲哚。在三乙胺存在下,在回流的乙醇中,1-(N,N-二烷基氨基甲酰基甲基)和1-氰基甲基4-二甲基氨基-吡啶溴的类似的环加成反应也导致具有高非对映选择性的二螺环戊基-3,3'-双氧吲哚。基于1 H NMR数据和单晶结构,阐明了双螺环戊基3,3'-双恶吲哚的立体化学。
A Facile Synthesis of Pechmann Dyes
作者:Henning Hopf、Peter G. Jones、Alina Nicolescu、Elena Bicu、Lucian M. Birsa、Dalila Belei
DOI:10.1002/chem.201400329
日期:2014.5.5
A facilesynthesis of Pechmann dyes has been accomplished by the reaction of substituted N‐phenacyl‐4‐dimethylaminopyridinium halides with dimethyl maleate in the presence of DBU. Based on a related 4‐DMAP elimination product and an isolated monolactone intermediate a reaction mechanism has been proposed. The scope of this synthetic method is determined by the availability of α‐haloaroyl or heteroaroyl
A direct and highly selective synthesis of octahydropyrrolo[2,1,5-cd]indolizin-6-one derivatives has been accomplished by a double dipolar cycloaddition of olefinic dipolarophiles to p-(dimethylamino)pyridinium ylides.
The reaction between 4-dimethylaminopyridine (DMAP) and 2-bromoacetophenone(s) readily gives 1- [2-(4-substitutedphenyl)-2-oxoethyl]-4-(dimethylamino)pyridinium bromide (1–14). Action of aqueous NaOH on 1–8 generates the corresponding pyridinium ylide (15–22), which is isolated as a colored stable crystalline solid. Addition of 15–22 to dimethylacetylene dicarboxylate (DMAD) gives dimethyl 3-(subs