Efficient Synthesis of α-Haloboronic Esters via Cu-Catalyzed Atom Transfer Radical Addition.

The synthesis of α-haloboronic esters via atom transfer radical addition (ATRA) is constrained due to its limited range of compatible substrates or the need to manipulate the olefin coupling partners. Herein, we present a novel approach for their synthesis via Cu-catalyzed ATRA to vinyl boronic esters. The catalyst is proposed to mediate a traditionally inefficient halogen atom transfer of the α-boryl radical intermediate, thus significantly expanding the range of participating substrates relative to established methods. The forty-eight examples illustrate that a wide range of radical precursors, including primary, secondary, and tertiary alkyl halides, readily add across both unsubstituted and α-substituted vinyl pinacol boronic esters. Further, a one-pot, two-step protocol is presented for direct access to an array of α-functionalized products. Finally, the synthetic utility of this methodology is demonstrated in the synthesis of an ixazomib analogue.

Synthesis of Unsymmetrical Vicinal Diamines via Directed Hydroamination.

Vicinal diamines are a common motif found in biologically active molecules. The hydroamination of allyl amine derivatives is a powerful approach for the synthesis of substituted 1,2-diamines. Herein, the rhodium-catalyzed hydroamination of primary and secondary allylic amines using diverse amine nucleophiles, including primary, secondary, acyclic, and cyclic aliphatic amines to access a wide range of unsymmetrical vicinal diamines, is presented. The utility of this methodology is further demonstrated through the rapid synthesis of several bioactive molecules and analogs.