Eco-Friendly Methodology to Prepare N-Heterocycles Related to Dihydropyridines: Microwave-Assisted Synthesis of Alkyl 4-Arylsubstituted-6-chloro-5-formyl-2-methyl-1,4-dihydropyridine-3-carboxylate and 4-Arylsubstituted-4,7-dihydrofuro[3,4-b]pyridine-2,5(1H,3H)-dione
Here we describe the efficient synthesis of alkyl 4-arylsubstituted-6-chloro-5-formyl-2-methyl-1,4-dihydropyridine-3-carboxylates and 4-arylsubstituted-4,7-dihydro-furo[3,4-b]pyridine-2,5(1H,3H)-diones via microwave-accelerated reaction of alkyl 4-arylsubstituted-2-methyl-6-oxo-1,4,5,6-tetrahydro-3-pyridinecarboxylates with the appropriate reagents. This eco-friendly approach to these valuable dihydropyridine derivatives does not involve the harsh or highly contaminating conditions common in classical heating and offers a reduction or even elimination of solvent use and recovery, simplification of the work-up procedures, facility of scale up, and low energy consumption, in addition to moderate to higher yields.
facile, efficient and environment-friendly protocol for the synthesis of 6-chloro-5-formyl-1,4-dihydropyridine derivatives has been developed by the convenient ultrasound-mediated reaction of 2(1H)pyridone derivatives with the Vilsmeier-Haack reagent. This method provides several advantages over current reaction methodologies including a simpler work-up procedure, shorter reaction times and higher yields
series of variously substituted 5-carboxy-6-methyl-3,4-dihydro-2(1H)-pyridone derivatives were synthesized and their oxidation potentials determined by cyclic voltammetry. The resulting 2-pyridone structure and a tricyclic heterocycle which was formed during an attempted synthesis of 4-(2-hydroxyphenyl) substituted 3,4-dihydro-2(1H)-pyridone were confirmed by single crystal X-ray crystallography.
4-Aryl substituted 5-alkoxycarbonyl-6-methyl-3,4-dihydropyridones have been prepared in one-pot condensation from Meldrum's acid, methyl acetoacetate and the appropriate benzaldehyde in the presence of ammonium acetate using microwaveirradiation without solvent. This rapid method produced pure products in high yields (81–91%) due essentially to a specific non-thermal microwave effect (17–28%) by conventional
Oxygen-bridged tetrahydropyridines, hexahydropyridines, and dihydropyridones via a Hantzsch-like synthesis with 4-(2-hydroxyphenyl)but-3-en-2-one
作者:Jan Světlík、Igor Goljer、František Tureček
DOI:10.1039/p19900001315
日期:——
Substituted oxygen-bridged tetrahydro-2-pyridones and tetrahydropyridines (4) and (7) were synthesized by condensation of 4-(2-hydroxyphenyl)but-3-en-2-one (1) with Meldrum's acid (2) and 3-aminocrotononitrile, respectively, in the presence of ammonium acetate. Analogous cyclo-condensations of (1) with methyl 3-amino-2,4-dicyanobut-2-enoate (8) and methyl 3-amino-2-cyanopentene-2-dioate (10) led to