No abstract

3-Acetylcoumarin (1) was utilized as a key intermediate for the synthesis of 2-aminothiazole derivative 3 via bromination of 1 to afford acetylbromide 2 followed by treatment with thiourea or via Biginelli reaction of 1. Treatment of 3 with 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde, 2-methyl-4H-benzo[d][1,3]oxazin-4-one, furo[3,4-b]pyrazine-5,7-dione or 2-methyl-5,6,7,8-tetrahydro-4H-benzothieno[2,3-d][1,3]oxazin-4-one afforded diazine derivatives 4-7. Also, pyridopyrimidine 8 was obtained via a one pot reaction of 6-aminothiouracil, p-chlorobenzaldehyde and 3-acetylcoumarin. Moreover, refluxing of 6-aminothiouracil with one equivalent amount of 2 afforded the thiazolopyrimidine 9, while the pyrrolothiazolopyrimidine 10 was revealed when two equivalent amounts of 2 was used. Furthermore, treatment of enamine 11 with 2-aminobenzothiazole or 6-aminothiouracil afforded the pyrimidine derivatives 12 and 13, respectively. Transamination of enamine 11 with m-anisidine followed by cyclization of the resulting enaminone 14 gave the desired quinoline 15. Also, treatment of 11 with thiophenol in dioxane gave the mercapto derivative 16. Moreover, coupling of 11 with 4,6-dimethyl-1H-pyrazolo[3,4-b]pyridin-3-yl-diazonium chloride, followed by complete cyclization of the resulting product afforded the pyridopyrazolothiazine 19 via the intermediate 18. Furthermore, the pyrazolopyrimidine 20 was revealed via a one pot condensation of 11, 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one and ammonium acetate. The thiadiazine derivatives 21-23 were obtained via treatment of 2 with the corresponding o-aminothiols. Desulphonation of 23 afforded the pyrazolotriazine 24. Finally, reaction of 2 with 2-hydroxybenzaldehyde gave benzofuran derivative 25. Representative compounds of the synthesized products were evaluated as antioxidant agents.

Tetra-n-butylammonium fluoride (TBAF) is an organic compound with the formula C16H36FN. It can exist as anhydrous or hydrated (C16H42FNO3). It is soluble in water and THF and utilized as a base in the preparation of triple monoamine reuptake inhibitors, conjugated dienoic acid esters, and polyacetylenic glucosides. This review aims to summarize the chemistry of TBAF.

Synthesis and Antioxidant Evaluation of Some New 3-Substituted Coumarins. -From the synthesized new title compounds the coumarins (VII), (XII), and (XVI) exhibit a high antioxidant activity in comparison to ascorbic acid. -(HAMAMA, W. S.; BERGHOT, M. A.; BAZ, E. A.; GOUDA*, M. A.; Arch. Pharm. (Weinheim, Ger.) 344 (2011) 11, 710-718, http://dx.