1.1: 82 percent / Cs2CO3 / acetonitrile / Heating 2.1: DIBAL-H / CH2Cl2 / -78 °C 2.2: KH; CS2; MeI / tetrahydrofuran / 20 °C 2.3: n-Bu3SnH; AIBN / benzene / Heating 3.1: 98 percent / TBAF / tetrahydrofuran / Heating 4.1: O2; Rose bengal; DIPEA / CH2Cl2 / -78 °C / Irradiation 4.2: 61 percent / NaBH4; H2O / CH2Cl2 / 20 °C View Scheme