Pd-Catalyzed Stereoselective Construction of Benzo-Fused Decalines with a Quaternary Carbon.

The Pd-catalyzed stereoselective construction of decalins with one-carbon units bearing heteroatoms at the ring junction is described. The Pd-catalyzed cyclization of silyl enol ether resulted in exclusive formation of the cis isomer (89%, >100/1 cis/trans). On the contrary, Pd-catalyzed carboiodination and carboborylation (with oxidative workup) provided products in 56% yield (1/>100 cis/trans) and 69% yield (1/11 cis/trans), respectively.