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Indian Journal of Chemistry -Section B (IJC-B) >
IJC-B Vol.51B [2012] >
IJC-B Vol.51B(07) [July 2012] >
| Title: | Facile synthesis of new substituted aryl and heteroarylflavones by thermal and microwave assisted Suzuki-Miyaura coupling reaction |
| Authors: | Joshi, Vidya
Hatim, Jaywant Govind |
| Keywords: | Suzuki-Miyaura coupling
Flavones
Biphenyl derivatives
Boronic acids
4′-bromoflavone
Microwave heating |
| Issue Date: | Jul-2012 |
| Publisher: | NISCAIR-CSIR, India |
| 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%. |
| Page(s): | 1002-1010 |
| CC License: |  CC Attribution-Noncommercial-No Derivative Works 2.5 India |
| ISSN: | 0975-0983(Online); 0376-4699(Print) |
| Source: | IJC-B Vol.51B(07) [July 2012]
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