Methylenedioxyphthalic acid

The reaction of esters of methylenedioxyphthalic acid (387) with the imine (388) affords the ester-lactam (389) and hydrolysis of this to the lactam-acid followed by Arndt-Eistert homologation and cyclisation yields the ketone (390, R R =0). Reduction of this to the secondary alcohol (390, R =H, R =0H), followed by dehydration and aerial oxidation affords oxosangui-narine (391), from which sanguinarine can be prepared (Shamma and H. Tomlinson, J.org.Chem., 1978, 2852). A similar... 

In contrast to crinine, powellamine gave a purple color with concentrated sulfuric acid and was oxidized by potassium permanganate to 3,4-methylenedioxyphthalic acid. Structure CXLIV or the C-7—C-8 methylenedioxy isomer must be considered likely structures. The absolute configuration of powellamine has not been determined (22). 

It should be added that oxidation of sinactine with permanganate in neutral solution has yielded 6,7-dimethoxy-l-keto-l,2,3,4-tetrahydro-isoquinoline, but 3,4-methylenedioxyphthalic acid could not be obtained by this method (34). 

CgHeOe [(OH)g(COOH)a == 1 2 4 5], rhombic prisms, forming an anhydride and melting at 247-5°. These observations show that hydrastic acid is 4 5-methylenedioxyphthalic acid. Freund and Lachman formulated these degradation products of hydrastinine thus —... 

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