HETEROCYCLIC COMPOUNDS. PART XXXI. THE SYNTHESIS OF PARTIALLY METHYLATED ETHERS OF POLYHYDROXY COUMARINS

Partial tosylation of 4-methyl-5 :7-dihydroxycoumarin furnished 4-methyl-5-hydroxy-7-conmarinyl-p-­toluenesulphonate which could be methylated to 4-methyl-5-methoxy-7-conmarinyl-p-toluenesul­phonate. its detosylation afforded 4-methyl-5-methoxy-7-hydroxycoumarin. Partial tosylation of 4-methyl-7 :8-dihydroxycoumarin -provided 4-methyl-8-hyclroxy-7-coumariny14-bluenesulphonate ; its methrlation and subsequent detasylation yielded 4-methyl-7-hydroxy-8-methomyeoumarin_s while the partial methylation of 4-methyl-7 :S-dihydroxyconmarin furnished the isotneric 4-rnethyl-7-methoxy-S­hydroxveoumarin. 5-Hydraxy.6-methoxy-4 :7-climethyleouinaritt was prepared by the alkaline persul­phate oxidation of 5.0-rnesyl derivative of 5-hydroxy-4 :7-dimethylcoumarin, followed by its methylation and subsequent demesylation. 4-Methyl-5 :7-dibydroxy-6-methoxycoumarin was prepared by the alkaline persnlphate oxidation of di-O-mesyl derivative of 4-methyl-5 :7-dihydroxycoumarin, its methyla­tion and subsequent demesylation.