1.1: 46 percent / lipase PS-C / diisopropyl ether / 18 h 2.1: 90 percent / potassium carbonate / methanol 3.1: lithium diisopropylamide / tetrahydrofuran / -78 °C 3.2: tetrahydrofuran / -78 °C 4.1: TFA / CH2Cl2 / 10 h View Scheme

1.1: 46 percent / lipase PS-C / diisopropyl ether / 18 h 2.1: 90 percent / potassium carbonate / methanol 3.1: lithium diisopropylamide / tetrahydrofuran / -78 °C 3.2: tetrahydrofuran / -78 °C 4.1: TFA / CH2Cl2 / 10 h 5.1: potassium carbonate / acetone View Scheme