DFT mechanistic studies of boron-silicon exchange reactions between silyl-substituted arenes and boron bromides.

C-B bond forming reactions are important methodologies in modern synthetic chemistry, since many borylated organic substrates, ranging from alkanes and alkenes to arenes and heteroarenes, are useful intermediates for the synthesis of natural products, pharmaceuticals, and organic π-conjugated materials. Among numerous borylation methods, C-Si/B-Br exchange reactions have attracted increasing attention in recent years. While experimental exploration has been continually carried out for more than two decades, mechanistic insights into this type of reaction have not yet been clearly established. To address this deficiency of knowledge, we performed density functional theory (DFT) calculations to map out the reaction pathways for a range of boron-silicon exchange reactions between boron tribromide (BBr3) and trimethylsilyl-substituted arenes (TMSAr). Our computational analyses have disclosed the energetic, structural, and electronic properties for key stationary points on the potential energy surfaces (PES) in both the gas and solution (CH2Cl2) phases.

Contractive Annulation: A Strategy for the Synthesis of Small, Strained Cyclophanes and Its Application in the Synthesis of [2](6,1)Naphthaleno[1]paracyclophane.

A new synthetic strategy (contractive annulation) for the synthesis of highly strained cyclophanes has been conceived and its viability has been demonstrated through a nine-step synthesis of [2](6,1)naphthaleno[1]paracyclophane from [2.2]paracyclophane.