Fig. 1: Transformation of strained C–C σ-bonds in BCBs.
From: Umpolung reactivity of strained C–C σ-bonds without transition-metal catalysis
A Previous strategies for the transformation of bicyclo[1.1.0]butane (BCBs). B The regular Alder-ene reaction of bicyclo[1.1.0]butanes (BCBs) with activated alkenes. C Umpolung Alder-ene reaction of BCBs with electron-deficient alkenes.
