Pd-Catalyzed Asymmetric Intramolecular Aryl C-O Bond Formation with SDP(O) Ligand: Enantioselective Synthesis of (2,3-Dihydrobenzo[b][1,4]dioxin-2-yl)methanols

Employing a chiral spirodiphosphine monoxide ligand with 1,1'-spirobiindane backbone (SDP(O)), a desymmetrization strategy of Pd-catalyzed intramolecular asymmetric aryl C-O coupling of 2-(2-halophenoxy)propane-1,3-diols, was developed. The SDP(O) ligand shows much better results than its SDP counterpart. The protocol provides an efficient and highly enantioselective method for the synthesis of 2-hydroxymethyl-1,4-benzodioxanes. Density functional theory studies provide a model that accounts for the origin of the enantioselectivity.