Three-Component Synthesis of Di- and Tetrahydrofurans under Rhodium Catalysis

Significance

The rhodium-catalyzed synthesis of highly functionalized di- and tetrahydrofurans is reported via the three-component coupling of ­aldehydes, α-alkyl-α-diazoesters and dipolarophiles. The α-alkyl carbonyl ylides formed in situ are highly reactive towards dipolarophiles, offering the desired products in high yield and demonstrate broad substrate scope compared to unsubstituted or α-aryldiazoacetates. The reaction proceeds with excellent regio- and stereoselectivity in nearly all cases, which is rationalized by an asynchronous endo transition state.