Ethanol → (1,3-Dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl)acetic acid--1-[(3,4-diethoxyphenyl)methyl]-6,7-diethoxy-3,4-dihydroisoquinoline (1/1)

Participants

Reaction Steps

U.S. Pat. Nos. 4,814,336 and 4,820,838 disclose 1-(3',4'-diethoxybenzyl)-6,7-diethoxy-3,4-dihydroisoquinolinium-theophylline-7-acetate (Depogen). According to U.S. Pat. No. 4,820,838, Depogen is prepared by reacting equimolar amounts of 1-(3',4'-diethoxy-benzyl)-6,7-diethoxy-3,4-dihydro-isoquinoline with theophylline-7-acetic acid in an alcohol (preferably ethanol or isopropanol), cooling to precipitate a solid, and then filtering off the solid. In the process of U.S. Pat. No. 4,820,838 the crystalline monohydrate of 1-(3',4'-diethoxy-benzyl)-6,(7-diethoxy-3,4-dihydro-isoquinolinium-theophylline-7-acetate and if desired of pure 1-(3',4'-diethoxybenzyl)-6,7-diethoxy-3,4-dihydro-isoquinolinium-theophylline-7-acetate free of contaminating oxidation products is prepared by reacting 1-(3',4'-diethoxy-benzyl)-6,7-diethoxy-3,4-dihydro-isoquinoline with theophylline-7-acetic acid in the presence of water and one or more organic solvents, and if desired dehydrating the 1-(3',4'-diethoxy-benzyl)-6,7-diethoxy-3,4-dihydro-isoquinolinium-theophylline-7-acetate-monohydrate thus obtained. The organic solvent may be dichloromethane, a ketone such as acetone, or an alcohol such as isopropanol.

Provenance & Evidence