methanesulfonic acid in chloroform Cyclization; Heating;

nitric acid; acetic acid

1.1: t-BuLi / diethyl ether; pentane / 1 h / -78 °C 1.2: ZnCl2 / tetrahydrofuran / 1 h 1.3: 70 percent / Pd(dba)2; dppf / tetrahydrofuran / 18 h / 20 °C 2.1: 86 percent / LiBH4 / diethyl ether; methanol; tetrahydrofuran / 0 - 20 °C 3.1: 76 percent / PPA; MeSO3H / CHCl3 / Heating View Scheme

1: 86 percent / LiBH4 / diethyl ether; methanol; tetrahydrofuran / 0 - 20 °C 2: 76 percent / PPA; MeSO3H / CHCl3 / Heating View Scheme

1.1: 90 percent / H2SO4 / 16 h / Heating 2.1: t-BuLi / diethyl ether; pentane / 1 h / -78 °C 2.2: ZnCl2 / tetrahydrofuran / 1 h 2.3: 70 percent / Pd(dba)2; dppf / tetrahydrofuran / 18 h / 20 °C 3.1: 86 percent / LiBH4 / diethyl ether; methanol; tetrahydrofuran / 0 - 20 °C 4.1: 76 percent / PPA; MeSO3H / CHCl3 / Heating View Scheme