Fig. 5. The influence of the substituent at the β-position of bicyclo[1.1.0]butanes.^a.

a Reaction conditions: BCB 1a’ (0.2 mmol), alkene 2 (0.1 mmol), Na₂SO₄ (0.17 mmol), 80 °C in DMSO (0.1 mL) under argon, 24 h, isolated yield.