Acceptorless dehydrogenative condensation: synthesis of indoles and quinolines from diols and anilines
作者:Delia Bellezza、Ramón J. Zaragozá、M. José Aurell、Rafael Ballesteros、Rafael Ballesteros-Garrido
DOI:10.1039/d0ob01964j
日期:——
The use of diols and anilines as reagents for the preparation of indoles represents a challenge in organic synthesis. By means of acceptorless dehydrogenative condensation, heterocycles, such as indoles, can be obtained. Herein we present an experimental and theoretical study for this purpose employing heterogeneous catalysts Pt/Al2O3 and ZnO in combination with an acid catalyst (p-TSA) and NMP as
使用二醇和苯胺作为制备吲哚的试剂代表了有机合成中的挑战。通过无受体的脱氢缩合,可以获得诸如吲哚的杂环。本文中,我们针对此目的进行了实验和理论研究,将多相催化剂Pt / Al 2 O 3和ZnO与酸催化剂(p-TSA)和NMP作为溶剂。在我们优化的条件下,二醇过量已减少至2当量。这代表了重大进步,并允许使用其他二醇。已使用2,3-丁二醇或1,2-环己二醇,得到2,3-二甲基吲哚和四氢咔唑。另外,已将1,3-丙二醇用于制备喹啉或天然和合成的聚甲基吡啶。
Metal and Oxidant Free Construction of Substituted‐ and/or Polycyclic Indoles: A Useful Alternative to Bischler and Related Syntheses
作者:Giacomo Mari、Lucia De Crescentini、Gianfranco Favi、Stefania Santeusanio、Fabio Mantellini
DOI:10.1002/ejoc.202000845
日期:2020.9.7
wide range of substitutedindoles, including complex polycyclic‐architectures were easily assembled by means of a Amberlyst 15H catalyzed synthesis that employs 1,2‐diaza‐1,3‐dienes and anilines. The metal and oxidant free methodology proposed here is characterized by good yields, total and predictable regioselectivity, and the ability to provide electron withdrawing substitutedindoles.
Addition reactions of heterocyclic compounds. Part 77. Reaction of dimethyl acetylenedicarboxylate with 2- and 3-alkyl substituted indoles and the formation of (1 + 1 DMAD–CH<sub>4</sub>O) adducts
作者:Roy M. Letcher、Michael C. K. Choi、R. Morrin Acheson、Richard J. Prince
DOI:10.1039/p19830000501
日期:——
Dimethyl acetylenedicarboxylate (DMAD) adds to 1,3-dimethylindole in moist acetic acid to give 2-substituted adducts. The dienone formulation for a product from 1,2,3-trimethylindole and DMAD has been confirmed by making use of proton-coupled 13C n.m.r. spectra. The generality of the formation of this (1 + 1 DMAD-CH4O) adduct is shown by the preparation of a further five new dienones including two
乙炔二羧酸二甲酯(DMAD)在潮湿的乙酸中加到1,3-二甲基吲哚中,生成2-取代的加合物。由1,2,3-三甲基吲哚和DMAD制成的产品的二烯酮配方已通过使用质子耦合的13 C nmr光谱得到证实。制备另外五个包括二个双环[9,3,1]五羟基十六烷二酮的新的二烯酮显示了这种(1 +1 DMAD-CH 4 O)加合物形成的一般性。
Iridium/Acid Cocatalyzed Direct Access to Fused Indoles via Transfer Hydrogenative Annulation of Quinolines and 1,2-Diketones
Herein, we present an unprecedented iridium/acid cocatalyzed construction of fused indoles via transfer hydrogenative annulation of nonactivated quinolines and 1,2-diketones. The products are assembled via initial reduction followed by selective coupling of 1,2-diketones with the N and C8 sites of the quinolyl skeleton. The developed synthetic method features operational simplicity, readily available feedstocks, applicability for streamline synthesis of functional molecules, high step and atom efficiency, and generation of water as the byproduct.
Zirconium Hydrazinediido Complexes Derived from Cyclic Hydrazines and Their Role in the Catalytic Synthesis of 1,7-Annulated Indoles
作者:Solveig A. Scholl、Hubert Wadepohl、Lutz H. Gade
DOI:10.1021/om301235d
日期:2013.2.11
Reaction of cyclic 1,1'-disubstituted hydrazines with the bis(dimethylamido)zirconium complex [Zr(N-Xyl)(2)N-py} (NMe2)(2)] (1) in the presence of dmap yielded the hexacoordinate zirconium hydrazinediido complexes [Zr(N-Xyl)(2)N-py}(=NNC9H10)(dmap)(2)] (2) and [Zr(N-Xyl)(2)N-py} (=NNC12H8)(dmap)(2)] (3). Hydrazinediides are thought to be key intermediates in the zirconium-catalyzed reaction of cyclic 1,1'-disubstituted hydrazines and disubstituted alkynes to yield 1,7-annulated indoles. Their basic structural motif is found in 5-HT3 receptor antagonists such as Cilansetron.