Selective C–C and C–H Bond Activation/Cleavage of Pinene Derivatives: Synthesis of Enantiopure Cyclohexenone Scaffolds and Mechanistic Insights

The continued development of transition-metal-mediated
C–C
bond activation/cleavage methods would provide even more opportunities
to implement novel synthetic strategies. We have explored the Rh­(I)-catalyzed
C–C activation of cyclobutanols resident in hydroxylated derivatives
of pinene, which proceed in a complementary manner to the C–C
bond cleavage that we have observed with many traditional electrophilic
reagents. Mechanistic and computational studies have provided insight
into the role of C–H bond activation in the stereochemical outcome
of the Rh-catalyzed C–C bond activation process. Using this
new approach, functionalized cyclohexenones that form the cores of
natural products, including the spiroindicumides and phomactin A,
have been accessed.