Header menu link for other important links
X
The reactions of phenols with α,β-unsaturated aromatic acids in presence of polyphosphoric acid: Synthetic and mechanistic studies
P L MAJUMDER, S CHATTERJEE, N MUKHOTI
Published in -
2001
Volume: 78
   
Issue: 43750
Pages: 743 - 755
Abstract
The reactions of cinnamic acid with phenol itself, catechol, hydroquinone, pyrogallol and 2-naphthol in presence PPA were studied and that with resorcinol was reinvestigated. With phenol itself and hydroquinone were obtained 3,4-dihydro-4-phenylcoumarin (1r) and 6-hydroxy-3,4-dihydro-4-phenylcoumarin (1s), respectively, as the sole products. Catechol and pyrogallol, on the other hand, afforded, besides the corresponding 3,4-dihydrocoumarins, viz. 8-hydroxy-3,4-dihydro-4-phenylcoumarin (1t) and 7,8-dihydroxy-3,4-dihydro-4-phenylcoumarin (1u), as the major products, 5,6-dihydroxy-3-phenylindanone (5b) and the chalcone 1-(2′,3′,4′-trihydroxy)-3-phenylpropan-2-en-1-one (3d), respectively, as minor products. But contrary to earlier observation, resorcinol was found to give 7-hydroxy-3,4-dihydro-4-phenylcoumarin (1v) instead of 7-hydroxyflavanone (4e). 2-Naphthol, on the other hand, afforded the chalcone derivative 1-|2′-hydroxynaphthyl|-3-phenylpropan-2-ene-1-one (7) as the exclusive product. The yields of the major products in the above reactions were 50-67% except that with phenol itself yielding 1r in 40% yield. The structures of all the products 1r, 1s, 1t, 1u, 1v, 3d, 5b and 7 were established from their various spectral (IR, 1H and 13C NMR and mass) data. Evidence for plausible mechanisms of formation of the above products was provided.
About the journal
JournalJournal of the Indian Chemical Society
Publisher-
ISSN0019-4522