PhPAd‐DalPhos: Ligand‐Enabled, Nickel‐Catalyzed Cross‐Coupling of (Hetero)aryl Electrophiles with Bulky Primary Alkylamines

PhPAd‐DalPhos: Ligand‐Enabled, Nickel‐Catalyzed Cross‐Coupling of (Hetero)aryl Electrophiles with Bulky Primary Alkylamines:

The incredible bulk: A new nickel(II) pre‐catalyst featuring the PhPAd‐DalPhos ancillary ligand is effective for the challenging cross‐coupling of sterically hindered primary alkylamines and (hetero)aryl halides under mild conditions.

Abstract

The base metal‐catalyzed C−N cross‐coupling of bulky α,α,α‐trisubstituted primary alkylamines with (hetero)aryl electrophiles represents a challenging and under‐developed class of transformations that is of significant potential utility, including in the synthesis of lipophilic active pharmaceutical ingredients. Herein, we report that a new, air‐stable Ni(II) pre‐catalyst incorporating the optimized ancillary ligand PhPAd‐DalPhos enables such transformations of (hetero)aryl chloride, bromide, and tosylate electrophiles to be carried out for the first time with substrate scope rivalling that achieved using state‐of‐the‐art Pd catalysts, including room temperature cross‐couplings of (hetero)aryl chlorides that are unprecedented for any catalyst (Pd, Ni, or other).