Abstract
o-Lithio 2,3-; 3,4-; 3,5-; 2,5- and 2,4-dimethoxy-N-methyl-benzamides upon condensation with propylene oxide give corresponding dimethoxy-3-methyl-3, 4-dihydroisocoumarins. The method has been used to synthesise (±)-6-methoxy mellein. 3-Methyl-6,7-dimethoxy-3,4-dihydroisocoumarin has been synthesised by an acid catalysed cyclisation reaction. The dihydroisocoumarins have been dehydrogenated to respective isocoumarins.
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Bhide, B.H., Brahmbhatt, D.I. Isocoumarins: Part 4. Synthesis of 5,6-dimethoxy, 6,7-dimethoxy, 7,8-dimethoxy, 5,7-dimethoxy, 5,8-dimethoxy-3-methyl-isocoumarins and a new synthesis of (±)-6-methoxy mellein. Proc. Indian Acad. Sci. (Chem. Sci.) 89, 525–532 (1980). https://doi.org/10.1007/BF02881086
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DOI: https://doi.org/10.1007/BF02881086