Chalcones belong to the flavonoid family which constitutes one of the major classes of naturally occurring oxygen heterocyclic compounds. The , -unsaturated carbonyl system of chalcones possesses two electrophilic reactive centers allowing them to participate in addition reactions via attack to the carbonyl group (1,2-addition) or involving the -carbon (1,4-conjugate addition), leading to the synthesis of promising bioactive heterocyclic compounds. The purpose of this review is to present a systematic survey of the most recent literature that uses chalcones in the synthesis of biologically active 5and 6-membered nitrogen heterocycles such as pyrroles, indoles, isoxazoles, imidazoles, pyrazoles, indazoles, triazoles, tetrazoles, pyridines and pyrimidines. Efficiency, easy-to-handle and cheap reagents, alternative heating conditions and greener protocols will be highlighted. In this review we will cover the literature since the beginning of the 21 century in more than 400 publications.

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Chalcones as Versatile Synthons for the Synthesis of 5- and 6-membered Nitrogen Heterocycles

Synthesis, spectroscopic characterization and biological evaluation studies of Schiff's base derived from naphthofuran-2-carbohydrazide with 8-formyl-7-hydroxy-4-methyl coumarin and its metal complexes.

The main purpose of this paper is to provide an insight into the biological activities of pyrazole derivatives which contain the carbohydrazide moiety.

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Pyrazole carbohydrazide derivatives of pharmaceutical interest.

Isoxazole is an azole with an oxygen atom next to the nitrogen. Isoxazole rings are found in some natural products, such as ibotenic acid and also found in a number of drugs, including COX-2 inhibitor valdecoxib. Furoxan, a nitric oxide donor is containing isoxazolyl group & found in many β-lactamase resistant antibiotics, such as cloxacillin, dicloxacillin and flucloxacillin. The synthetic androgenic steroid danazol also has an isoxazole ring. The substituted isoxazoles are well developed in literature to posses significant biological activities. The disubstituted and trisubstituted isoxazoles have been reported to exhibit broad range of biological activities such as antimicrobial activity, analgesic activity, antiinflammatory activity, antioxidant activity, anticancer activity, CNS activity, antitubercular activity and miscellaneous activities like GABA agonistic activity, inhibitory activity, antihypertensive activity, and glutamate transporter activity. The present review summarizes up to date information of various biological activities of isoxazole analogs.

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Isoxazole – a potent pharmacophore

Some novel substituted-3-{[(1E)-(substituted-2-furyl)-methylene]amino}quinazolin-4(3H)-one (5, 6, 7) a-f were synthesized by a multi-step process. These synthesized compounds are characterized by various spectroscopic techniques and evaluated for their antitubercular and anticancer activities. Biological activity indicated that some of the title compounds are potent antitubercular and anticancer agents.

Synthesis, antitubercular and anticancer activities of substituted furyl-quinazolin-3(4H)-ones.

Ethyl naphtho[2,1-b]furan-2-carboxylate (2) on reaction with hydrazine hydrate in presence of acid catalyst in ethanol medium affords naphtho[2,1-b]furan-2-carbohydrazide (3). The reaction of substituted acetophenones (4a-c) with aromatic aldehydes (5a-e) produces chalcones (6a-o) via the Claisen condensation. The reaction of naphtho[2,1-b]furan-2-carbohydrazide (3) with chalcones (6a-6o) in presence of acetic acid as catalyst in dioxane produces 1-(naphtho[2,1-b]furan-2-yl-carbonyl)-3,5-disubstituted-2,3-dihydro-1H-pyrazoles (7a-o). The structures of newly synthesized compounds have been established by elemental analysis and spectral studies. The compounds 7a-o have been evaluated for their antimicrobial activity and some selected compounds evaluated for antiinflammatory, analgesic, anthelmintic, diuretic and antipyretic activities.

https://www.ijpsonline.com/articles/synthesis-and-activity-evaluation-of-21naphtho21-b-furan2ylcarbonyl35disubstituted23dihydro1hpyrazoles.pdf

Synthesis and Activity Evaluation of 2-(1-naphtho[2,1-b]furan-2-yl-carbonyl)-3,5-disubstituted-2,3-dihydro-1H-pyrazoles.

2-Hydroxy-1-naphthonitrile (1) on treatment with different α-haloketones affords corresponding 2-acyl-3-aminonaphtho[2,1- b ]furans (2a-2d). The compounds 2a-2d on reacting with ammonium thiocyanate and benzoyl chloride produce N-acyl-N1-(2-acylnaphtho[2,1- b ] furan)thiourea (3a-3d), which on further refluxing with sodium hydroxide yield 2-mercapto-4-acylnaphtho[2,1- b ]furo[3,2-d]pyrimidines (4a-4d). These on stirring with chloroacetic acid give S-(4-acylnaphtho[2,1- b ]furo[3,2-d]pyrimidine)-mercaptoacetic acid (5a-5d). The structures of newly synthesized compounds have been established by elemental analysis and spectral studies. In addition, they have been screened for antimicrobial, diuretic, and antiinflammatory activities. The compounds 4c, d, 5c and 5d were found to be active against bacteria and fungi. The compounds 4c, 5a, 5c, and 5d showed significant diuretic activity having T/S values of 0.89, 0.68, 0.62, and 0.68, respectively. The compounds 5c and 5d showed considerable antiinflammatory activity having percentage protection value of 55.64 and 63.7.

https://www.ijpsonline.com/articles/synthesis-and-pharmacological-evaluation-of-2mercapto4substitutednaphtho21-b-furo32-d-pyrimidines.pdf

Synthesis and pharmacological evaluation of 2-mercapto-4-substituted-naphtho[2,1- b ]furo[3,2- d ]pyrimidines

Synthesis of Novel Naphtho[2,1‐b]furo‐pyrazolyl, ‐isoxazolyl and ‐pyridyl Derivatives as Potential Antimicrobial Agents.

The treatment of chalcones 2a-f with substituted hydrazines in ethanol results in the formation of 3-(3-aminonaphtho[2,1-6]fur-2-yl)-5-arylpyrazolines 3a-1. The reaction of these chalcones 2a-f with hydroxylamine hydrochloride in presence of catalytic amount of hydrochloric acid affords 3-(3-aminonaphtho[2,1-b]fur-2-yl)-5-arylisoxazolines 4a-f. The synthesis of another biheterocycle, 2-amino-3-cyano-4-aryl-6-(3-aminonaphtho[2,1-b]fur-2yl)pyridines 5a-f is accomplished by reacting chalcones 2a-f with malanonitrile in presence of ammonium acetate. All the newly synthesized compounds are characterized by elemental analysis and spectral studies, and evaluated for antimicrobial activity.

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D. A. Prathima Mathias

Papers

Synthesis and Activity Evaluation of 2-(1-naphtho[2,1-b]furan-2-yl-carbonyl)-3,5-disubstituted-2,3-dihydro-1H-pyrazoles.

Synthesis and pharmacological evaluation of 2-mercapto-4-substituted-naphtho[2,1- b ]furo[3,2- d ]pyrimidines

Synthesis of Novel Naphtho[2,1‐b]furo‐pyrazolyl, ‐isoxazolyl and ‐pyridyl Derivatives as Potential Antimicrobial Agents.

Synthesis of novel naphtho[2,1- b ]furo pyrazolyl, isoxazolyl and pyridyl derivatives as potential antimicrobial agents