Total Synthesis of Lucidimines/Ganocalicines A/B, Sinensine E, and Ganocochlearine E

The central tetracyclic framework shared by the Ganoderma alkaloids─lucidimines/ganocaclicines A and B, sinensine E, and ganocochlearine E─appears inherently predisposed to arise from a diyne-nitrile cyclotrimerization event. A Co(I)-catalyzed intramolecular [2 + 2 + 2]-alkynenitrile cyclotrimerization has been employed to accomplish the first racemic and enantioselective total syntheses of sinensine E, lucidimine A, and ganocochlearine E, thereby establishing/revising their assigned stereochemical structures.