Metal-Free Cascade Approach toward Polysubstituted Indolizines from Chromone-Based Michael Acceptors
摘要:
An efficient cascade transformation toward indolizine-based molecules has been developed. This process leads to the rapid construction of two C-N bonds and one C-C bond without the need of any metal catalysis. The approach involves easily accessible chromone-based Michael acceptors and propargylamine derivatives as starting materials. This cascade constitutes a novel and very competitive alternative to the well reported strategies using pyridine or pyrrole derivatives for accessing the indolizine ring with substituents at uncommon C-positions
Benzopyrans. Part 42. Reactions of 4-Oxo-4<i>H</i>-1-benzopyran-3-carbaldehyde with some active methylene compounds in the presence of ammonia
作者:Chandra Kanta Ghosh、Anirban Ray、Amarendra Patra
DOI:10.1002/jhet.5570380632
日期:2001.11
The title aldehyde 1 in the presence of ammonia gives the pyridine derivatives 9-11 respectively with acetylacetone, diethyl malonate and ethyl cyanoacetate, and ethyl (or methyl)-l-benzopyrano[4,3-b]pyri-dine-3-carboxylate 22 (or 23) with ethyl (or methyl) acetoacetate. Acetylacetone pretreated with ammonia condenses with 1 giving the fused pyridine 24. Ammonia converts the ester 6 to the pyridine
Simple and ecofriendly synthesis of dihydropyrimidinones (thiones), dihydropyridines, and pyridines using 3-formylchromones as substrates assisted by a recyclable Preyssler heteropolyacid
作者:Laura M. Sanchez、Gustavo Pasquale、Ángel Sathicq、Diego Ruiz、Jorge Jios、Andrea L. Ferreira de Souza、Gustavo P. Romanelli
DOI:10.1002/hc.21340
日期:2016.9
Several dihydropyrimidinones/thiones, 1,4-dihydropyridines, and pyridine derivatives were prepared in very good yields and purity values. The corresponding reactions were carried out by employing a bulk Preysslerheteropolyacid H14[NaP5W29MoO110] as an efficient and recyclable catalyst. The preparation of pyridine derivatives was carried out not through a usual procedure, i.e., the opening of the γ-pyrone