Browsing by Author "Kulkarni, Geetha M."

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5-phenylpyridazinones - A serendipitous route from coumarins
(2008-07-07)
Ghate, Manjunath D.
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Jadhav, Vithal B.
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Shastri, Lokesh A.
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Kulkarni, Manohar V.
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Kulkarni, Geetha M.
A new route of the ring transformation has been discovered during the reaction of 4-bromomethylcoumarins with hydrazine hydrate leading to the formation of pharmacologically important pyridazinones in a single step with very high yields. These so obtained pyridazinones have the potential for further functional group interconversions. (C) 2008 Elsevier Ltd. All rights reserved.
Unusual Anisotropic Effects from 1,3-Dipolar Cycloadducts of 4-Azidomethyl Coumarins
(2010-01-01)
Kusanur, Raviraj A.
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Kulkarni, Manohar V.
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Kulkarni, Geetha M.
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Nayak, Susanta K.
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Row, Tayur N. Guru
4-Bromomethylcoumarins (1) reacted with sodium azide in aqueous acetone to give 4-azidomethyl-coumarins (2), which underwent 1,3-dipolar cycloaddition with acetylenic dipolarophiles to give triazoles (3). These triazoles (3) have been found to exhibit interesting variations in the chemical shifts of C(3)-H and C(4)-methylene protons. Protonation studies indicate that the shielding effect of the C(3)-H of coumarin is due to pi-electrons of the triazole ring, further supported by diffraction and computational studies.