Cytochrome P450 that catalyzes an intramolecular C-C phenol coupling of (S)-reticuline in magnoflorine biosynthesis. Catalyzes the formation of (S)-corytuberine from (S)-reticuline, and also, with a lover efficiency, the 4'-O-demethylation of codamine to produce orientaline, and subsequent C-C-phenol coupling of orientaline. Can also use (R,S)-norreticuline, (R,S)-orientaline, (S)-N-methylcoclaurine and (S)-coclaurine as substrates, but not (R,S)-6-O-methyllaudanosoline, (R,S)-6-O-methylnorlaudanosoline, (R,S)-laudanine, (R,S)-norlaudanine, (R,S)-4'-O-methyllaudanosoline, (R,S)-pseudocodamine, (R,S)-norpseudocodamine, (R,S)-laudanosine, (R,S)-norlaudanosine, (R,S)-laudanosoline or (R,S)-norlaudanosoline. (S)-reticuline + O2 + reduced [NADPH--hemoprotein reductase] = (S)-corytuberine + 2 H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] Inhibited by ketoconazole. Belongs to the cytochrome P450 family.