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

Abstract

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.

A more sustainable Wohl–Ziegler bromination: Versatile derivatization of unsaturated FAMEs and synthesis of renewable polyamides

“…Moreover, the allylic bromination was also carried out in bulk to avoid any solvent waste. Notably, microwave assisted allylic brominations of methyloleate or Wohl–Ziegler brominations on water did not lead to the desired monoallylic bromide, which is in contrast to results reported for other substrates (e.g., benzylic substrates) . Furthermore, we observed that mainly a conventional bromination of the double bond occurred in the microwave mediated brominations, most probably due to the faster decomposition of AIBN or NBS, which resulted in higher bromine concentrations.…”

3,4-Dihydro-2(1H)-Pyridones as Building Blocks of Synthetic Relevance

“…MW-assisted synthesis (MWAS) of alkyl 4-arylsubstituted-6-chloro-5-formyl-2-methyl-1,4-dihydropyridine-3-carboxylates (44) and 4-arylsubstituted-4,7-dihydrofuro [3,4-b]pyridine-2,5(1H,3H)-diones (45) from 3,4-DHPo's (43) were reported (Figure 7). [95] US-assisted synthesis (USAS) was also used to obtain chloroformyl derivatives from 3,4-DHPo's as starting materials (Figure . 7).…”

One Pot Synthesis of Novel Cyanopyridones as an Intermediate of Bioactive Pyrido[2,3-d]Pyrimidines

“…1−5 The combination of solvent-free reaction conditions and microwave irradiation leads to large reduction in reaction times, enhancement in conversion and sometimes in selectivity with several advantages of the eco-friendly approach, termed green chemistry. 6,7 Bicyclic nitrogen-containing heterocyclic compounds, such as purines 8−10 quinazolines 11−13 and pyridopyrimidines 14−17 are well-known pharmacophores in drug discovery. Pyrido [2,3-d]pyrimidines have been the most thoroughly investigated of the four possible pyrido pyrimidine ring systems and hence, this scaffold is associated with a wide range of biological activities, such as dihydrofolate reductase (DHFR) inhibitory activity, antitumor activity, 18−21 adenosine kinase inhibition 22 and tyrosine kinase inhibition.…”