Enzymic phenol oxidation. Part III. Head-to-head coupling of 1,2,3,4-tetrahydro-7-hydroxy-1-(4-hydroxyphenethyl)-6-methoxy-2-methylisoquinoline with homogenised Wasabia japonica Matsumura and hydrogen peroxide
Enzymic phenol oxidation of 1,2,3,4-tetrahydro-7-hydroxy-1-(4-hydroxyphenethyl)-6-methoxy-2-methylisoquinoline (I) with homogenised Wasabia japonica Matsumura in the presence of hydrogen peroxide was found to give, by head-to-head, C–O–C coupling, the bisphenethylisoquinoline (IV), characterised as the triacetyl derivative by spectroscopic methods. In contrast, 1,2,3,4-tetrahydro-7-hydroxy-6-methoxy-1-(4-methoxyphenethyl)-2-methylisoquinoline (IX) was recovered almost quantitatively after treatment with Wasabia japonica or potato peel homogenates. Suggestions are made concerning the active sites of these oxidising enzymes.