Ligand‐Controlled Palladium‐Catalyzed Carbonylation of Alkynols: Highly Selective Synthesis of α‐Methylene‐β‐Lactones. Issue 48 (17th September 2020) - Ge, Yao
Abstract: The first general and regioselective Pd‐catalyzed cyclocarbonylation to give α‐methylene‐β‐lactones is reported. Key to the success for this process is the use of a specific sterically demanding phosphine ligand based on N ‐arylated imidazole (L11 ) in the presence of Pd(MeCN)2 Cl2 as pre‐catalyst. A variety of easily available alkynols provide under additive‐free conditions the corresponding α‐methylene‐β‐lactones in moderate to good yields with excellent regio‐ and diastereoselectivity. The applicability of this novel methodology is showcased by the direct carbonylation of biologically active molecules including natural products. Abstract : The advanced Pd/L11 system enables highly regioselective carbonylation of alkynols for synthesis of a wide range of 4‐membered α‐methylene‐β‐lactones.