Abstract:Coumarins are naturally occurring oxygen heterocyclic compounds having multifarious medicinal properties, hence used as lead compounds for designing new potent analogs. The chromene butenoic acid 3 and the benzochromene butenoic acid 4 which are derived from the reaction of glyoxalic acid with 3-acetylcoumarin and 3-acetylbenzocoumarin, respectively, were reacted with different nitrogen and carbon nucleophiles to give new heterocyclic compounds. The structures of the prepared compounds were elucidated by IR, 1 H-NMR, and mass spectroscopy. Some of the newly prepared compounds were tested in vitro against a panel of four human tumor cell lines namely; hepatocellular carcinoma (liver) HepG2, colon cancer HCT-116, human prostate cancer PC3, and mammary gland breast MCF-7. Also they were tested as antioxidants. Almost all of the tested compounds showed satisfactory activity.

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Chemical transformations of chromone‐3‐carbonitrile (1) with some substituted hydrazines, namely, thiosemicarbazide, S‐methyl/benzyldithiocarbazate, 7‐chloro‐4‐hydrazinoquinoline, and 3‐hydrazino‐5,6‐diphenyl‐1,2,4‐triazine, led to substituted pyrazoles 2, 5–8. Ring opening of carbonitrile 1 followed by recyclization with 3‐amino‐1,2,4‐triazole and 2‐aminobenzimidazole gave triazolo[1,5‐a]pyrimidine 9 and pyrimido[1,2‐a]benzimidazole 10, respectively. Treatment of carbonitrile 1 with some heterocyclic amines produced 2‐amino‐3‐substituted‐chromones 11 and 12. The novel 3‐hydroxychromeno[4,3‐b]pyrazolo[4,3‐e]pyridin‐5(1H)‐one (13) was efficiently synthesized from the ring conversion of carbonitrile 1 with cyanoacetohydrazide. A mixture of chromeno[2,3‐b]naphthyridine 14 and chromeno[4,3‐b]pyridine 15 was obtained from base catalyzed transformation of carbonitrile 1 with malononitrile dimer. A diversity of novel annulated chromeno[2,3‐b]pyridines 16–22 was also synthesized. Chromeno[2,3‐b]pyrrole‐2‐carboxylate 23 was obtained from the reaction of carbonitrile 1 with ethyl chloroacetate. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data.

The reaction of pyrazolobenzothienopyrimidine-3-carbaldehyde 1 with thiocarbohydrazide afforded the Schiff's base 3. The latter compound reacted with some electrophilic reagents to give 1,2,4-triazoles 4-6 and 1,2,4-triazines 7-9. Treatment of compound 3 with 2-cyano-3,3-bis(methylthio)acrylonitrile gave the corresponding 5-amino-4-cyano-3-methylthiopyrazole derivative 11. The reaction of pyrazole 11 with carbon disulfide afforded dithioxopyrazolopyrimidine 12. Acylation of compound 11 by using acetic anhydride yielded acetamide 13. On the other hand, the cyclocondensation of pyrazole 11 with acetic anhydride in pyridine yielded pyrazolopyrimidine derivative 14. The reactivity of compound 11 towards formamide and phenylisothiocyanate to give the pyrazolopyrimidines 15 and 16 was studied. The newly synthesized compounds were screened for their antimicrobial activity.