1.1: 90 percent / potassium cyanide; 18-crown-6 / dimethylformamide / 0.67 h / 0 °C 2.1: CuI / diethyl ether; hexane / 3.5 h / -78 °C 2.2: 20 percent / acetic acid; water / diethyl ether; hexane 3.1: 91 percent / 4-(dimethylamino)pyridine; pyridine / CH2Cl2 / 0.33 h 4.1: t-BuSH / methanol / 25 °C / Photolysis View Scheme

4-(N,N-dimethlyamino)pyridine; triethylamine in dichloromethane Ring cleavage; silylation; Heating;