Rh(II)-Catalyzed Monocyclopropanation of Pyrroles and Its Application to the Synthesis Pharmaceutically Relevant Compounds.

Here we report Rh(II)-catalyzed monocyclopropanation reactions on pyrroles in the presence of aryldiazoacetates, providing the corresponding dearomatized products with high levels of enantioselectivity (up to >99% ee). Under the catalysis of Rh2(R-p-PhTPCP)4, a broad range of pyrrole substrates and aryldiazoacetates are shown to be compatible. Utilizing these valuable chiral building blocks, we further demonstrate the application of this transformation by synthesizing a homo-ß-proline analog and a ß-aminocarboxylic acid (ß-ACC) derivative from the monocyclopropanated product.

Regio- and Stereoselective Synthesis of Functionalized Dihydropyridines, Pyridines, and 2H-Pyrans: Heck Coupling of Monocyclopropanated Heterocycles.

A palladium-catalyzed coupling between aryl halides and monocyclopropanated pyrroles or furans has been developed, leading to valuable six-membered N- and O-heterocycles. As the key step, a selective cleavage of the non-activated endocyclic C-C bond of the 2-heterobicyclo-[3.1.0]hexane framework is achieved. The developed method offers access to highly functionalized piperidines, pyridines, and pyrans that are challenging to access by traditional methods.