Advances in the Construction of Boryl Cyclobutanes

Abstract

Boryl-substituted cyclobutanes have emerged as valuable building blocks that merge the structural rigidity and strainenabled reactivity of four-membered rings with the versatile synthetic utility of organoboron chemistry. Here, the recent advances in the synthesis of boryl-substituted cyclobutanes, a class of strained, sp³-rich building blocks that combine the structural rigidity of cyclobutanes with the exceptional versatility of organoboron chemistry, have been summarized. Emphasis is placed on strategies that exploit boronate complex reactivity and 1,2-migration processes to overcome the inherent challenges associated with four-membered ring formation. Thermal, photochemical, and transition-metalcatalysed approaches are discussed, highlighting how strain-release, radical polar crossover, and σ-bond activation enable efficient and stereocontrolled cyclobutane construction. Key mechanistic insights that govern selectivity and reactivity also have been outlined across diverse platforms.2.