S. C. Joshi, K. N. Trivedi
Sep 1, 2010
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Journal
Bulletin des Sociétés Chimiques Belges
Abstract
7-Hydroxy-3-phenyl-[4H]-1-benzopyran-4-one 1a was condensed with 2-bromocyclohexanone to yield the corresponding ether 2a which on alkaline hydrolysis gave tetrahydrodibenzofuran derivative 3a the pyran ring being opened up during this reaction. Compound 3a was dehydrogenated with DDQ and the benzopyrone ring was constructed on dibenzofuran nucleus with sodium and ethyl formate to provide 3-phenyl-[4H]-benzofuro (3,2-g)-1-benzopyran-4-one 5a. Compound 5a was also synthesized by first converting 3a into corresponding [4H]-1-benzopyran-4-one 6a and then subjecting it to dehydrogenation. A similar series of reactions were employed for 7-hydroxy-8-methyl-3-phenyl-[4H]-1-benzopyran-4-one 1b and 7-hydroxy-2-methyl-3-phenyl-[4H]-1-benzopyran-4-one 1c to obtain 2-hydroxy-1-methyl-3-phenylacetyl dibenzofuran 4b and 2-methyl-3-phenyl-[4H]-benzofuro (3,2-g)-1-benzopyran-4-one 5c respectively.