Scheme 2. Substrate scope of propargylic esters and alkenes. Reaction conditions: 1 (0.2 mmol), 2 (0.4 mmol), Rh₂(OPiv)₄ (1 mol%), 1,2-dichloroethane (2 mL), 80 °C, 48 h. ^a NMR yield with 4-nitrotoluene as the internal standard. Note: 3es was unstable during purification with silica gel.