Fig. 5: Crossover experiment.

Reaction conditions: 1z (0.5 mmol), 1c (0.5 mmol), and Rh₂(OAc)₄ (0.025 mmol, 2.5 mol%) in 2.0 mL DCM, 2a (1.5 mmol), and DCM (2.0 mL) was added dropwise in 10 min at room temperature. Isolated yields for 3za and 3ca.