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。
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.
1-[(4-Chlorobenzoyl)methyl]-4-(<i>N</i>,<i>N</i>-dimethylamino)pyridinium bromide sesquihydrate and 1-[(4-bromobenzoyl)methyl]-4-(<i>N</i>,<i>N</i>-dimethylamino)pyridinium bromide sesquihydrate
作者:T. V. Sundar、V. Parthasarathi、K. Sarkunam、M. Nallu、B. Walfort、H. Lang
DOI:10.1107/s0108270104010923
日期:2004.7.15
The title compounds, C15H16ClN2O+ . Br- . 1.5H(2)O and C15H16BrN2O+ . Br- .1.5H(2)O, are isomorphous. The benzene ring is oriented nearly normal to the pyridine ring in both compounds. The molecular packing is mainly influenced by intermolecular O - H ... O and O - H ... Br interactions, as well as weak intramolecular C - H ... O interactions. The H2OBr- units form an extended water-bromide chain, with a bridging water molecule on a twofold axis.
Synthesis of some new indolizines
作者:K. Sarkunam、M. Nallu
DOI:10.1002/jhet.5570420102
日期:2005.1
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