Synthesis of (-)-terpestacin via catalytic, stereoselective fragment coupling: siccanol is terpestacin, not 11-epi-terpestacin.

(-)-Terpestacin (1a, naturally occurring enantiomer) and (+)-11-epi-terpestacin (1b) were prepared using catalyst-controlled, stereoselective intermolecular reductive couplings of alkyne 4 and aldehyde 5. Related to enantioselective methods developed in our laboratory, these stereoselective fragment couplings were instrumental in confirming that "siccanol" is not 11-epi-terpestacin, but in fact is (-)-terpestacin itself.