Preparing 7-alkoxybenzofurans and intermediates used therein.

摘要

In a synthesis of 6-hydroxy-7-alkoxy-5-benzofuranyl methyl ketone, a known intermediate in the synthesis of khellin and anti-atherosclerotic analogues thereof, pyrogallol is converted to 3,6,7-benzofurantriol triacetate using zinc chloride and chloroacetanitrile, then catalytically reduced and deactoxylated at the 3-position to yield the corresponding 2,3-dihydrofuran. This substance is subjected to a Fries rearrangement to the corresponding diol, the phenolic hydroxyl group of which is then selectively alkylated. The ketone is selectively alkoxylated at the 4-position using lead tetraacetate, ceric ammonium nitrate or thallium (III) nitrate in an alkanol solvent to yield further known chemical intermediates in the preparation of khellin and analogues thereof.