The Synthesis of Certain BisISOQuinoline Derivatives Structurally Related to Emetine

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Abstract
α ω-Bis(3:4-dihydro-6:7-dimethoxy-1 - isoquinolyl) - propane, - butane, and −2- methylpropane have been prepared, the latter for the first time and the structures confirmed by comparing the ultra-violet light spectrophotometric measurements with those for ethyl γ-(3:4-dihydro-6:7-dimethoxy-1-iso-quinolyl) butyrate. The prepared compounds have been hydrogenated to give the corresponding tetrahydroisoquinoline derivatives and the structures confirmed by spectrophotometric measurements and by comparison of the pKa values with those of the corresponding dihydrocompounds. The tetrahydroisoquinoline derivatives are of comparable basic strength with emetine. Biological results are not yet available. An alternative route to the necessary amides required as intermediates for the above has been found to yield amides free from the unwanted cyclic imides, but the yields are not as good as by the other route. The use of a potassium bisulphate sodium sulphate mixture for ring-closing the amides has been found to yield cyclic imides instead of the required isoquinoline derivatives.