We report the structural revision via synthesis of the abietane diterpenoid plebeianiol A. The synthesis was accomplished by a short and convergent sequence that featured our previously established cobaltcatalyzed hydrogen-atom-transfer-induced radical bicyclization. We further connected plebeianiol A as the likely biogenetic precursor to another previously reported ether-bridged abietane. Finally, we demonstrated that the key cyclization event is efficient with the A-ring diol protected as two different cyclic acetals or in unprotected form.Letter pubs.acs.org/OrgLett
We designed and executed an expedient synthesis of a complex analogue of the potent immunosuppressive natural product brasilicardin A. Our successful synthesis featured application of our recently developed MHAT-initiated radical bicyclization, which delivered the targeted, complex analogue in 17 steps in the longest linear sequence. Unfortunately, this analogue showed no observable immunosuppressive activity, which speaks to the importance of the structural and stereochemical elements of the natural core scaffold.
The enantioselective
syntheses of (−)-coniine, DAB-1, and nectrisine have been developed,
utilizing a complementary strategy of enzyme- and transition metal-catalyzed
reactions. The initial stereocenter was set with >99% enantioselectivity
via an enzyme-catalyzed hydrocyanation reaction. Substrate incompatibilities
with the natural enzyme were overcome by tactical utilization of ruthenium-catalyzed
olefin metathesis to functionalize an enzyme-derived (R)-allylic fragment. The piperidine and pyrrolidine alkaloid natural
products were obtained by a route that leveraged regio- and stereoselective
palladium-catalyzed 1,3-substitutive reactions.
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