Synthesis of oxo aporphines an unusual photo cyclization photo reduction of 2 3 di aryl delta 2 pyrroline 4 5 diones
Castedo, L.; Saa, C.; Saa, J.M.; Suau, R.
Journal of Organic Chemistry 47(3): 513-517
The photocyclization of substituted 2,3-diaryl-.DELTA.2-pyrroline-4,5-diones, with a forced cis-stilbene geometry, afforded the corresponding phenanthrene derivatives. Concomitant photoreduction of the C-4 carbonyl group to methylene was observed when triethylamine was used as acid scavenger. The role of the amine in the photocyclization and photoreduction steps is discussed in terms of the results obtained with different amines (triethylamine, pyridine and tert-butylamine). The naturally occurring oxoglaucine, lysicamine and dicentrinone were synthesized in good to acceptable yields by Fremy's salt oxidation of the photocyclized products.