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Pechmann reaction of 4-hydroxycoumarins and thiocoumarins with cyclohexanone and ethyl cyclopentanone-2-carboxylates |
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| Authors: | J R Merchant N M Koshti K M Bakre |
| Abstract: | The Pechmann reaction of 4-hydroxycoumarins with cyclohexanone and ethyl cyclopentanone-2-carboxylates affords 1,2,3,4-tetrahydro2]benzopyrano4,3-c]1]benzopyran-5,12-diones and cyclopenta3′,4′]pyrano-3,2-c]1]benzopyran-4,11-diones. Dehydrogenation of the former yields 2]benzopyrano4,3-c]1]benzopyran-5,12-diones. Alkaline hydrolysis of a typical compound Va affords 2-hydroxy-2′-carboxydeoxybenzoin which on boiling with acetic anhydride gives an isocoumarin derivative. |
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