Sequential EDA/HAT Enables C(sp³)–C(sp³) Cross-Dehydrogenative Coupling: Accessing Non-Canonical Amino Acids with Quaternary Carbon Centers from Activated and Non-Activated Alkanes

Current strategies for the alkylation of amino acids via C(sp³)-H functionalization require the use of transition metals, often in the presence of excess peroxides at high temperatures. Herein, we developed a unique electron-donor-acceptor (EDA) system using aryl halides and <i>N</i>-phenylglycine derivatives to achieve a C(sp³)-C(sp³) cross-dehydrogenative coupling that gives access to noncanonical amino acids. This metal- and photocatalyst-free protocol enables functionalization of ethers and unactivated alkanes via a hydrogen-atom transfer (HAT) process performed by an in situ generated aryl radical. The reaction proceeds via radical-radical coupling, which enables the formation of sterically demanding quaternary carbon centers and delivers site-selective α-functionalized <i>N</i>-phenylglycine moieties even when appended to complex bioactive molecules or small peptides.