The scholarly interest in recent decades has been considerable towards the paradigm shift of substituting planar arene moieties with three-dimensional (3D) saturated bicyclic analogues, a concept popularly referred to as "escape from flatland". Among those 3D skeletons, bicyclo[2.1.1]hexanes (BCHs) have captured the focus of synthetic chemists due to their utility as bioelectronic substitutes for ortho-or meta-substituted arenes to enhance both the physicochemical and pharmacokinetic profiles of bioactive drugs. There has been a heightened emphasis on formulating efficient synthetic methodologies for BCHs, and the [2π + 2σ] cycloaddition of bicyclo[1.1.0]butanes (BCBs) with 2π-synthons emerges as a notable synthetic strategy due to its broad substrate compatibility and effectiveness. Blanchard pioneered this approach in 1966 with the inaugural application of thermally driven [2π + 2σ] cycloadditions of BCBs with alkenes to yield captivating mono-BCHs. Very recently, the [2π + 2σ] cycloadditions via radical pathway between BCBs and alkenes were flourished, pioneered by Glorius and Brown . Furthermore, Leitch's study on the Lewis acid catalyzed cycloaddition of imines and BCBs led to a rapid development of the [2π + 2σ] dipolar cycloadditions. These aforementioned elegant works provided a variety of mono-or fused-BCHs (Scheme 1a). Despite the widespread usage of spirocycles in bioactive natural and synthetic compounds, the synthesis of BCHs incorporating spirocycles has been constrained. Brown reported the pioneering synthesis of two examples of spiro-BCHs in 2022 through photoinduced cycloaddition with BCBs and 1,1-disubstituted alkenes. Subsequently, Li reported three cases of constructing spiro-BCHs from pyridine BCBs through the selective activation of remote bonds catalyzed by diboron compounds, while Wang also employed a similar strategy to achieve the synthesis of a spiro-BCH (Scheme 1b). These protocols for spiro-BCHs features exocyclic terminal olefins as 2π-partner and radical cycloaddition pathway. Considering spirocycles bearing unique rigidity and three-dimensional configuration could lead to potential biological properties, developing [2π + 2σ] cycloaddition reactions of BCBs to furnish the valuable diversity spiro-BCHs with diverse structure is still highly demanded.