13 14 Aradhana Industrial Development Corporation

Goregaon, India

13 14 Aradhana Industrial Development Corporation

Goregaon, India
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Joshi V.,13 14 Aradhana Industrial Development Corporation | Govind Hatim J.,13 14 Aradhana Industrial Development Corporation
Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry | Year: 2012

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(OCOCH 3) 2 catalyst, in solvent DMF(N,N-dimethylformamide) and base, aqueous Na 2CO 3 (2N) for 6-12 hr, at 110°C, yield 30-70%, ii) conventional heating with Pd[(C 6H 5) 3P] 4 catalyst, in DMF and base, aq. Na 2CO 3 (2N) for 6-12 hr, at 110°C, yield 40-72% and iii) Microwave heating with Pd[(C 6H5) 3P] 4 catalyst, in solvent (DMF+H 2O, 5:2) and base, aq. Na 2CO 3 (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%.


Joshi V.,13 14 Aradhana Industrial Development Corporation | Hatim J.G.,13 14 Aradhana Industrial Development Corporation
Indian Journal of Heterocyclic Chemistry | Year: 2011

Flavones 7a-k having aryl and heteroaryl substituents at 3-position were synthesized in a Panasonic microwave-oven by Suzuki-Miyaura cross coupling reaction using 3-bromoflavone 5 and substituted aryl and heteroaryl boronic acids 6a-k with tetrakistriphenylphospine-palladium |(C6H 6)3P]4Pd as catalyst and N,N-dimethylformamide (DMF)+ H2O (9:4) as solvent, and aq.Na2CO3(2N) as base.

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