Synthesis of Ferrocene-Fused Pyrans through Alkynoxy-Directed C–H Activation/Cyclization

We have developed palladium-catalyzed C–H activation and cyclization of alkynyl ferrocenyl ethers with various alkynes, providing ferrocene-fused pyran derivatives. As a preliminary result, we also achieved the asymmetric version of this reaction with high enantioselectivity, providing the first example of the catalytic asymmetric synthesis of an enantio-enriched ferrocene-fused oxacycle.