α-Borylcarbene Precursors: Design, Generation, and Synthetic Opportunities

Abstract

a α-Boryl carbenes combine the high reactivity of carbenes with the synthetic versatility of organoboron compounds, enabling unique strategies for molecular construction. However, their practical use has long been limited by the intrinsic instability of α-boryl diazo intermediates and the difficulty of generating these carbenes in a controlled manner. In recent years, significant progress has been achieved through the development of well-designed precursors that balance stability with efficient carbene generation. This review summarizes recent advances in α-boryl carbene precursor design and reactivity.The discussion is organized according to precursor classes, including diazo compounds and sulfonyl hydrazones, alkynes, cyclopropenes, and haloalkanes. Key design principles that enable controlled carbene formation are highlighted together with representative synthetic transformations. These developments demonstrate how molecular design has transformed αboryl carbene chemistry into a practical platform for organoboron synthesis.