The two isopavines (le and lf) have been synthesised, and the former has been found to correspond to the structure of the alkaloid reframoline. The two related pavines were isolated and identified as by-products. In one case some evidence was obtained for a C1→C3-benzyl migration in the isoquinoline system.
constitutes a variation and represents the first recorded “hydration” of a 1,2-dihydroisoquinoline to a 4-hydroxy-1,2,3,4-tetrahydroisoquinoline. The correct structure of remrefine is confirmed. Some speculations on the biosynthesis of pavine and isopavine alkaloids are also included.