Diethyl Ether → 2,2-Dimethyl-4-(1-naphthyl)-7-chromanol

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Reaction Steps

To a stirred solution of methyl-lithium in ether (120 ml., 1.9M solution) at room temperature was added over 0.5 hours finely powdered 3,4-dihydro-7-hydroxy-4-(1-naphthyl) coumarin (14.5g, 0.05 moles). After refluxing for 1 hour a purple solid precipitated out of solution and the reaction mixture was allowed to cool, acidified with dilute hydrochloric acid and extracted with ether (3×). The combined ether extracts were dried and removal of solvent gave a dark coloured oil which was refluxed overnight in glacial acetic acid. The glacial acetic acid was removed in vacuo and the residue dissolved in ether, washed with water, saturated sodium bicarbonate solution and dried. Removal of solvent gave an extremely viscous oil, column chromatography of which on silica, eluting with 40°-60° petrol: ether (gradually increasing concentration of ether) gave the required chroman as a low melting pale yellow solid (9.4g., 76%).

Provenance & Evidence