AN ELEGANT SYNTHESIS OF SOME NATURALLY OCCURRING LINEAR ACETYLCHROMENES: EUPATORIOCHROMENE, METHYLEUPATORIOCHROMENE (ENCECALIN); EVODIONOL AND METHYLEVODIONOL

Article abstract of DOI:10.1016/0040-4020(82)80200-7

An elegant synthesis of linear acetylchromenes, viz eupatoriochromene, methyleupatoriochromene (encecalin), evodionol and methylevodionol, has been achieved by blocking the reactive position C-3 of the appropriate ketones with an iodo group, prenylation with 3-chloro-3-methylbut-1-yne and subsequent cyclisation.Regiospecific introduction of C-prenyl group in the less reactive position C-5 has been achieved by the reaction of the appropriate 3-iodo ketones with 2-methylbut-3-en-2-ol.The 5-prenyl ketones are also essential intermediates for the synthesis of linear acetylchromenes.