1: 1) BuLi / 1) hexane, THF, -30 deg C, 2) THF, -50 deg C to r.t., 2 h View Scheme

1: 1) BuLi / 1) hexane, THF, -30 deg C, 2) THF, -50 deg C to r.t., 2 h 4: 83 percent / Py / tetrahydrofuran / 1) -20 deg C, 0.5 h, 2) r.t., 3 h View Scheme

1: 1) BuLi / 1) hexane, THF, -30 deg C, 2) THF, -50 deg C to r.t., 2 h 4: 68 percent / PCC / CH2Cl2 / 2 h / Ambient temperature View Scheme