Abstract
In connection with the water soluble papaverine related compounds, syntheses of 6 kinds of 1-dihydroxybenzyl-6, 7-dimethoxy-3, 4-dihydroisoquinoline derivatives (IIa-f) were attempted. In the case of 2, 3-, 2, 4-, 2, 5- and 2, 6-dihydroxybenzyl derivatives, a resinification in benzylation of [bis (benzyloxy) phenyl] acetic acid (VIa-d), starting materials of amide (VIIIa-d) were found to be remarkable, therefore, instead of the preparation of amide by the condensation of VIIa-d and homoveratrylamine, the amide, mentioned above and 7-, 6-, 5- and 4-hydroxybenzofuran-2-one (IXa-d) were condensed to amides (Xa-d), which were later benzoylated to VIIIa-d. These amides were dehydrated to ring closure into 4 kinds of 1-[bis (benzyloxy) benzyl] derivatives and a further debenzylation gave two kinds of the expected compounds IIIa-b. In the case of 3, 4- and 3, 5-dihydroxybenzyl derivatives, their amides (VIIIe-f) were prepared by the usual Schotten-Baumann method. However, the former compound produced 1-[3, 4-bis (benzyloxy) benzyl] isoquinoline derivative (IIe) and (IIIe). The latter did not give any expected compound of either IIf or IIIf.
