Pseudobenzylisoquinoline alkaloids

The pseudobenzylisoquinoline alkaloids are fairly widespread in nature, being found among members of Berberidaceae, Annonaceae, Fumariaceae, and Ranunculaceae. The biogenesis of the pseudobenzylisoquinoline alkaloids assumes their formation from protoberberinium salts by C-8—C-8a bond scission in a Baeyer-Villiger-type oxidative rearrangement to produce the enamides of type 73 and 74. These amides may be further biotransformed either to rugosinone (76) type alkaloids by hydrolytic N-deformylation followed by oxidation or to ledecorine (75) by enzymatic reduction. These transformations were corroborated by in vitro studies (80-82). It is suggested that enamide seco alkaloids may be precursors of aporphine alkaloids (80), on one hand, and of cularine alkaloids (77), on the other. 

Valencia, E., Weiss, I., Shamma, M., Urzua, A., and Fajardo, V (1984) Dihydrorugosme, a pseudobenzylisoquinoline alkaloid from Berberis darwinii aad Berberis actinacantha. J. Nat. Prod. 47, 1050,1051. 

Two similar pathways have been reported (79) for the total synthesis of a pseudobenzylisoquinoline-type alkaloid, rugosinone (43), isolated as a minor component of Thalictrum rugosum. As shown in Scheme 8 the anion of N-benzoyl-l-cyano-6,7-methylenedioxy-l,2-dihydroisoquinoline (28) was reacted... 

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