Exploration of substrates scope^a,b,c,d.

^aReaction preformed with [RuCl₂(mesitylene)]₂ (0.025 eq.) and (S,S)-DPAE (0.05 eq.) heated in 2-propanol (0.3 mL) at 80 °C for 1 h. After cooling to room temperature, the catalyst was then added to the β-keto ester 1 (0.2 mmol, 1 eq.) and HCO₂H/EtN₃ (1.5 : 3, 1.5 eq.) in dioxane (1 mL).

^bIsolated yields.

^cdr determined by ¹H NMR analysis of the crude reaction mixture.

^der determined by chiral HPLC.

^eIsolated yields based on recovered start material.

^fNo reaction.

^gThe reaction gave a complicated mixture of product.