Regioselective Electrophilic Fluorination of Rationally Designed Imidazole Derivatives

We report the regioselective and direct functionalization of rationally designed imidazole derivatives through electrophilic fluorination with <i>N</i>-fluorobenzenesulfonimide enabled via in situ deprotonation with lithium 2,2,6,6-tetramethylpiperidine. Aided by a controlled protecting group switch, we were able to effectively target both the reactive 5- as well as the difficult to target 4-position of these molecules, leading to a series of fluorinated polysubstituted imidazoles in gram scale

Asymmetric Construction of Spirocyclopentenebenzofuranone Core Structures via Highly Selective Phosphine-Catalyzed [3 + 2] Cycloaddition Reactions

An efficient organocatalytic asymmetric [3 + 2] cycloaddition reaction between 3-substituted methylenebenzofuranone derivatives and diverse Morita–Baylis–Hillman carbonates to provide complex polysubstituted spirocyclopentenebenzofuranone scaffolds in a single step is reported. C2-symmetric phospholanes were efficient nucleophilic catalysts of this transformation under mild conditions, providing reaction products comprised of three consecutive stereocenters, including one all-carbon center, with excellent enantioselectivity

Assembly of Spirooxindole Derivatives Containing Four Consecutive Stereocenters via Organocatalytic Michael–Henry Cascade Reactions

A novel organocatalytic strategy for the synthesis of highly substituted spirocyclopentaneoxindoles was developed employing simple nitrostyrenes and 3-substituted oxindoles as starting materials. Michael–Henry cascade reactions, enabled through cinchona alkaloid organocatalysis, provided products in high yield and excellent enantioselectivity in a single step

Assembly of Spirooxindole Derivatives via Organocatalytic Iminium-Enamine Cascade Reactions

The assembly of complex spirocyclopentaneoxindoles via a novel organocatalytic iminium-enamine cascade process is reported. Reactions between 3-substituted oxindoles and α,β-unsaturated aldehydes catalyzed by second generation prolinol ethers provided the desired products in high yield with excellent levels of enantioselectivity in a single step