Studies in the Synthesis of Furochromones. Part-VI

Chemistry Department, Faculty of Science, M. S. University of Baroda, Baroda-390 002 Manuscript received 28 October 1979, revised 2 December 1980, accepted 9 June 1981 5-AIIyl-6-hydroxy-1,2,3,4-tetrahydroxanthone(Ia) and 7-allyl-6-hydroxy-5-methyl1,2,3,4-tetrahydroxanthone(ld) on acetylation followed by bromination and cyclization with alcoholic potassium hydroxide afforded 5'-methyl-1,2,3,4-tetrahydrofuro(3',2'-5,6)- xanthone(II) and 5,5'-dimethyl-1,2,3,4-tetrahydrofuro (2' ,3'-6,7)xanthone(lll) respectively. 8-AIIyl-7-hydroxy-1,2,3,4-tetrahydrocyclopenta(b) benzopyran-4-one(IV c) under similar condition gave 6-(2'-methyl-4'-hydroxybenzofuran-5'-yl)-6-oxo-6H-hexanoic acid(VI) instead or the expected 8-methyl-1,2,3,4-tetrahydrocyclopenta(b) furo(2,3-h)- benzopyran-4-one(V). Attempted synthesis of (V) through cyclization of (IV c) with cone. sulphuric acid followed by dehydrogenation with palladised charcoal or DDQ failed since dehydrogenation could not be achieved