Enantioselective Synthesis of 2,2‐Disubstituted Tetrahydrofurans: Palladium‐Catalyzed [3+2] Cycloadditions of Trimethylenemethane with Ketones

O rings: An approach to the title compounds has been developed utilizing a cycloaddition of trimethylenemethane with aryl ketones. The products are formed in up to a 96 % yield with 95 % ee. The reaction is catalyzed by palladium in the presence of L1, which possesses a stereogenic phosphorus atom, and only a single epimer at the phosphorus atom yields the active catalyst. Cp=cyclopentadiene, TMS=trimethylsilyl.