Conversion of (±)‐3‐ethyl‐3‐methyl phthalides to 3,3‐dimethyl‐3,4‐dihydroisocoumarins. Synthesis of 3‐methylmellein

Abstract

Abstract o ‐Lithio yV‐methyl benzamides ( 1a‐f ) upon alkylation with ethyl methyl ketone gave (±)‐3‐ethyl‐3‐methyl phthalides ( 2a‐f ), which upon treatment with concentrated H 2 SO 4 or anhydrous A1C1 3 furnished corresponding 3,3‐dimethyl‐3,4‐dihydroisocoumarins ( 3a‐f ) and 3‐methyl mellein ( 3g ).