Alcohol Mediated Synthesis of 4-Oxo-2-aryl-4H-chromene-3-carboxylate Derivatives from 4-Hydroxycoumarins
Manoj R. Zanwar, Mustafa J. Raihan, Sachin D. Gawande, Veerababurao Kavala, Donala Janreddy, Chun-Wei Kuo, Ram Ambre and Ching-Fa Yao*
*Department of Chemistry, National Taiwan Normal University, 88, Sec. 4, Tingchow Road, Taipei, Taiwan 116, R.O.C., Email: cheyaocfntnu.edu.tw
M. R. Zanwar, M. J. Raihan, S. D. Gawande, V. Kavala, D. Janreddy, C.-W. Kuo, R. Ambre, C.-F. Yao, J. Org. Chem., 2012, 77, 6495-6504.
DOI: 10.1021/jo301044y (free Supporting Information)
The unusual alcohol mediated reaction of 4-hydroxycoumarins and β-nitroalkenes leads to 4-oxo-2-aryl-4H-chromene-3-carboxylate (flavone-3-carboxylate) derivatives. The transformation occurs via the in situ formation of a Michael adduct, followed by the alkoxide ion mediated rearrangement of the intermediate. The effects of different media on the reaction were investigated.
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