The construction of C­(sp3)–Si bonds is important in synthetic, medicinal, and materials chemistry. In this context, reactions mediated by silyl radicals have become increasingly attractive but methods for accessing these intermediates remain limited. We present a new strategy for silyl radical generation via electroreduction of readily available chlorosilanes. At highly biased potentials, electrochemistry grants access to silyl radicals through energetically uphill reductive cleavage of strong Si–Cl bonds. This strategy proved to be general in various alkene silylation reactions including disilylation, hydrosilylation, and allylic silylation under simple and transition-metal-free conditions.

The direct functionalization of C(sp3)–H bonds is an attractive research topic in organic synthetic chemistry. The cross-dehydrogenative coupling (CDC) reaction provides a simple and powerful tool for the construction of C–C and C–heteroatom bonds. Recently, some progress has been made in the iron-catalyzed aerobic oxidative CDC reactions. Here, we present recent developments in the direct functionalization of C(sp3)–H bonds catalyzed by simple iron salts with molecular oxygen as the terminal oxidant.1 Introduction2 C(sp3)–C Bond Formation3 C(sp3)–N Bond Formation4 C(sp3)–S(Se) Bond Formation5 Conclusion and Outlook

We describe an unprecedented dual C–H functionalization of indolin-2-one via an oxidative C­(sp3)–H/N–H/X–H (X = N, C, S) cross-coupling protocol, which is catalyzed by a simple iron salt under mild and ligand-free conditions and employs air (molecular oxygen) as the terminal oxidant. This method is readily applicable for the construction of tetrasubstituted carbon centers from methylenes and provides a wide variety of spiro N-heterocyclic oxindoles.

Spiro pyrano[2,3-c]pyrazoles and spiro 1,4-dihydropyridines were obtained in high yields from different amine components under Dabco-based ionic liquid catalysis.

Single‐electron transfer (SET) plays a critical role in many chemical processes, from organic synthesis to environmental remediation. However, the selective reduction of inert substrates (Ep/2 < −2 V vs Fc/Fc+), such as ubiquitous electron‐neutral and electron‐rich (hetero)aryl chlorides, remains a major challenge. Current approaches largely rely on catalyst photoexcitation to reach the necessary deeply reducing potentials or suffer from limited substrate scopes. Herein, we demonstrate that cumulenes—organic molecules with multiple consecutive double bonds—can function as catalytic redox mediators for the electroreductive radical borylation of (hetero)aryl chlorides at relatively mild cathodic potentials (approximately −1.9 V vs. Ag/AgCl) without the need for photoirradiation. Electrochemical, spectroscopic, and computational studies support that step‐wise electron transfer from reduced cumulenes to electron‐neutral chloroarenes is followed by thermodynamically favorable mesolytic cleavage of the aryl radical anion to generate the desired aryl radical intermediate. Our findings will guide the development of other sustainable, purely electroreductive radical transformations of inert molecules using organic redox mediators.