Microwave Assisted Synthesis, Part 1: Rapid Solventless Synthesis of 3-Substituted Coumarins and Benzocoumarins by Microwave Irradiation of the Corresponding Enaminones

Abstract

The reactivity of enaminones toward a variety of reagents under microwave irradiation is reported. The results are compared with traditional solution methods.

Microwave Assisted Condensation Reactions of 2-Aryl Hydrazonopropanals with Nucleophilic Reagents and Dimethyl Acetylenedicarboxylate

“…The desired compounds were obtained in low yield, consequently we have modified this synthetic approach by condensing the methyl ketones with slightly excess of DMFDMA in the absence of solvent [26] (Scheme 1). In this case the reaction products 2b-g were obtained in almost quantitative yields yield on cooling in a much more economical synthesis.…”

“…The yield of products obtained with the microwave heating technique and the time taken to complete the reactions will be compared with those seen with conventional methods [8,26].…”

Synthesis and reactions of 2,6-bis[3-oxo-3-propanenitrile-2-(N,N-dimethylamino)methylene]pyridine

“…X-Ray crystal structure of compound 5b. In a similar manner, the enaminonitrile 3 reacted with hydroxylamine hydrochloride, in the presence of potassium carbonate, and afforded white solid of 2,6-bis[4-cyano-isoxazol-5-yl]pyridine (8) that not readily soluble in most of organic solvent. Compound 8 is assumed to be formed via the Michael type addition of the amino group of hydroxylamine to the enamine double bond in the enaminonitrile 3 [18][19][20][21] to form non-isolable intermediate 7 which underwent intramolecular cyclization via the loss of dimethylamine and water molecules to afford the isoxazole derivative 8 (type A, Scheme 2).…”

“…[5][6][7][8][9] On the other hand a great deal of interest has been focused on the synthesis of the functionalized pyridine derivatives due to their biological activities. [10][11][12][13] In view of these observations and in continuation of our previous work on the synthesis of heterocyclic systems for biological evaluations, [14][15][16][17] we report herein a facile route to various pyrazoles, isoxazoles, pyrimidines, pyrazolopyrimidine and…”

Synthesis of 1,3,4-Thiadiazoles, α -Pyranone ,Pyridine, Polysubstituted Benzene from 1,3,4-Thiadiazolyl Ethanone and Testing Against Tuberculosis Based on Molecular Docking Studies

“…Refluxing of enaminone 9 with 5-amino-3-(methylsulfanyl)-1H-pyrazole-4-carbonitrile in glacial acetic acid gave 7-{(5E)-5-[(4-methoxyphenyl)imino]-4-phenyl-4,5- Finally, hydrazonyl halides 5a,b has been reported to add to α,b-unsaturated carbonyl compounds to yield a mixture of isomeric pyrazolines 21,22 .…”