Enantio- and Diastereodivergent Cyclopropanation of Allenes by Directed Evolution of an Iridium-Containing Cytochrome.

Alkylidene cyclopropanes (ACPs) are valuable synthetic intermediates because of their constrained structure and opportunities for further diversification. Although routes to ACPs are known, preparations of ACPs with control of both the configuration of the cyclopropyl ( vs ) group and the geometry of the alkene ( vs ) are unknown. We describe enzymatic cyclopropanation of allenes with ethyl diazoacetate (EDA) catalyzed by an iridium-containing cytochrome (Ir(Me)-CYP119) that controls both stereochemical elements.

Mechanism-Based Design of an Amide-Directed Ni-Catalyzed Arylboration of Cyclopentene Derivatives.

A method for amide-directed Ni-catalyzed diastereoselective arylboration of cyclopentenes is disclosed. The reaction allows for the synthesis of sterically congested cyclopentane scaffolds that contain an easily derivatized boronic ester and amide functional handles. The nature of the amide directing group and its influence on the reaction outcome are investigated and ultimately reflect a predictably selective reaction based on the solvent and base counterion.