1: 87 percent / LDA; THF / hexamethylphosphoric acid triamide / 6 h / -78 - 20 °C 2: 85 percent / lithium aluminium hydride / tetrahydrofuran / 5 h 3: 95 percent / pyridine; DMAP / 26 h 4: dimethyl sulfide; BF3*Et2O / 2 h / -10 °C View Scheme