Pd(II)-catalyzed enantioselective C(sp3)–H arylation of cy-clopropanes and cyclobutanes guided by tertiary alkyla-mines.

Abstract

Strained aminomethyl-cycloalkanes are a recurrent scaffold in medicinal chemistry due to their unique structural features that give rise to a range of biological properties. Here, we report a palladium-catalyzed enantioselective C(sp3)–H arylation of aminome-thyl-cyclopropanes and -cyclobutanes with aryl boronic acids. A range of native tertiary alkylamine groups are able to direct C–H cleavage and forge carbon-aryl bonds on the strained cycloalkanes framework as single diastereomers and with excellent enantiomeric ratios. Cen-tral to the success of this strategy is the use of a simple N-acetyl amino acid ligand, which not only controls the enantioselectivity but also promotes -C–H activation of over other pathways. Computational analysis of the cyclopalladation step provides an understanding of how enantioselective C–H cleavage occurs and revealed distinct transition structures to our previous work on enantioselective desymme-trization of N-iso-butyl tertiary alkylamines. This straightforward and operationally simple method simplifies the construction of func-tionalized aminomethyl-strained cycloalkanes, which we believe will find widespread use in academic and industrial settings relating to the synthesis of biologically active small molecules.