3'-hydroxylation of (S)-N-methylcoclaurine. (S)-N-methylcoclaurine + O2 + reduced [NADPH--hemoprotein reductase] = (S)-3'-hydroxy-N-methylcoclaurine + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Alkaloid biosynthesis; (S)-reticuline biosynthesis; (S)-reticuline from (S)-norcoclaurine: step 3/4. Expressed at low levels in roots. Belongs to the cytochrome P450 family.