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

Isocoumarins: Part VIII-Synthesis of methoxy-and benzo-3-methylisocoumarins

“…The nonequivalence of benzylic protons must be due to the methoxyl functional group and the ring residue at position 5. Such type of observation has been reported by us earlier (Bhide and Brahmbhatt 1980).…”

“…Isocoumarins and their 3, 4-dihydroderivatives having C 3 methyl group and -OCH 3 or -OH groups in the aromatic ring are widely distributed in nature (Nishikawa 1933;Barry 1964;Gupta 1977). In our earlier work (Bhide and Shah 1980;Bhide and Brahmbhatt 1980) we have reported the synthesis of several such 3methylisocoumarins in which we have used heteroatom-directed ortholithiation as the key step. We report here another general synthesis of 3-methylisocoumarins by an acid-catalysed path starting with readily available aromatic aldehydes.…”