Product 6 then undergoes keto–enol tautomerism to form (S)-scoulerine, which is then methylated by SAM to form (S)-tetrahydrocolumbamine 7.
In this chemical process, product 6 transforms through keto–enol tautomerism into (S)-scouserie, and subsequently undergoes methylation with SAM to yield (S)-tetrahydrocolumbamine 7.