The Brønsted acid catalysis is widely regarded as one of the most effective methods for activating inert substrates and enabling unique reactivity. In this work, we introduce the first example of H-bond-assisted chalcogen exchange between arsine oxides and phosphine selenides under mild conditions, providing a powerful approach to the synthesis of arsine selenides. The reaction proceeds successfully in both protic and aprotic solvents and is accelerated by the presence of any nonaqueous acid. This newly discovered reaction is tested for various arsine oxides R3AsO (R = Ph, Et, nBu, iPr) and phosphine selenides R3PSe (R = Ph, Me, Et, tBu) and overall demonstrates high conversion, although the use of reagents with bulky substituents significantly hinders its efficiency. The reaction mechanism involves the formation of a four-membered cyclic transition state, which requires overcoming steric and electrostatic repulsion, as well as significant distortion of the reagents’ tetrahedral geometry. Hydrogen bonding with the As═O fragment helps to reduce electrostatic repulsion between the P═Se and As═O groups, making the formation of the cyclic intermediate more favorable.

Non-covalent interactions are a highly promising tool for the development of transition-metal-free chemospecific synthetic transformations. Here, we demonstrate the implementation of non-covalent interactions as a simple, precise, and flexible synthetic toolbox, allowing the controlled transformation of o-dimethylaminoaryloximes into nitriles and hard-to-reach nitrogen heterocycles under mild conditions. This diverse reactivity is activated via hydrogen bonding and facilitated via the “buttressing effect” of the substituents next to the NMe2 group. All transformations require only simple and easily available acids and solvents, which generally provide precise control over the direction of the reaction, allowing the selective synthesis of nitriles, fused pyrazoles, isoxazoles, and pyrroles.

Dispersion interactions serve as a driving force for ortho-lithiation: A significantly large and bulky substituent, rich in C−H bonds, attached to the pyridine nitrogen of 4-dimethylaminopyridine, st...

We demonstrate the effective utilization of steric interactions for flipping the lithiation of 4-dimethylaminopyridine (DMAP). Introduction of a Me3Si substituent to the position 1 of DMAP or simple ...