Total Synthesis of (−)-Macrocarpal C. Stereoselective Coupling Reaction with a Novel Hexasubstituted Benzene Cr(CO) 3 Complex as a Biomimetic Chiral Benzyl Cation Equivalent

The first total synthesis of (−)-macrocarpal C ( 3 ) is described. The synthesis features a highly stereoselective coupling reaction of silyldienol ether 6 with biomimetic benzyl cation species ( R )- and ( S )- B, which were generated from novel hexasubstituted benzene chromium tricarbonyl complexes ( R )- and ( S )- 17 . At the final step of the total synthesis, we developed the tris- O -demethylation of macrocarpal C trimethyl ether 34 under basic conditions using lithium p -thiocresolate. Moreover, spectroscopic evidence shows that the synthetic (−)- 3 is identical to natural macrocarpal G ( 4 ).