Please use this identifier to cite or link to this item:
|Title:||Facile synthesis of new substituted aryl and heteroarylflavones by thermal and microwave assisted Suzuki-Miyaura coupling reaction|
Hatim, Jaywant Govind
|Abstract:||Microwave assisted Suzuki-Miyaura coupling of 4'-bromoflavone 5 with substituted aryl and heteroarylboronic acids 6a-m gives high yields of aryl and heteroarylflavones 7a-m. Couplings have been carried out by three methods i) conventional heating with Pd(OCOCH3)2 catalyst, in solvent DMF(N,N-dimethylformamide) and base, aqueous Na2CO3 (2N) for 6-12 hr, at 110°C, yield 30-70%, ii) conventional heating with Pd[(C6H5)3P]4 catalyst, in DMF and base, aq. Na2CO3 (2N) for 6-12 hr, at 110°C, yield 40-72% and iii) Microwave heating with Pd[(C6H5)3P]4 catalyst, in solvent (DMF+H2O, 5:2) and base, aq. Na2CO3 (2N) for 2-9 min, yield 50-87%. The substrate 4′-bromoflavone 5 has been synthesized from o-hydroxyacetophenone 1 in 3 steps. Esterification of 1 with 4-bromobenzoyl chloride 2 with montmorillonite-KSF catalyst, DCE (1,2-dichloroethane) and Et3N (triethylamine) which gives 2-(4-bromobenzoyloxy)acetophenone 3. Baker-Venkataraman rearrangement of 3 with pyridine and KOH further gives 1-(4-bromophenyl)-3-(2-hydroxyphenyl)propane-1,3-dione 4, followed by cyclization of 4 with methanolic sulfuric acid (2.5%) which yields 4'-bromoflavone 5, yield 82%.|
|Appears in Collections:||IJC-B Vol.51B(07) [July 2012]|
Files in This Item:
|IJCB 51B(7) 1002-1010.pdf||128.14 kB||Adobe PDF||View/Open|
Items in NOPR are protected by copyright, with all rights reserved, unless otherwise indicated.