Stereoselective synthesis of (+)-euphococcinine and (-)-adaline.

We describe the syntheses of (+)-euphococcinine and (-)-adaline, two naturally occurring alkaloids containing a quaternary carbon bearing a nitrogen atom. Key features of the syntheses are a 3,3-sigmatropic rearrangement to give an all-carbon quaternary center, a ring-closing alkene metathesis to give an 8-membered ring, and the use of a single enantiomer of p-menthane-3-carboxaldehyde to make two natural alkaloids of opposite configuration.