DBN; iodine in diethyl ether Heating;

1.1: I2; DBN / diethyl ether / 15 h 1.2: 73 percent / DBN / benzene / 2.5 h / Heating 2.1: t-BuLi / tetrahydrofuran; pentane / 1 h / -78 °C 2.2: B(OMe)3 / tetrahydrofuran; pentane / 1 h / 0 °C 2.3: 84 percent / aq. TlOH / Pd(PPh3)4 / tetrahydrofuran; pentane / 3 h / 25 °C 3.1: 91 percent / aq. KOH / ethanol / 70 °C View Scheme

1.1: I2; DBN / diethyl ether / 15 h 1.2: 73 percent / DBN / benzene / 2.5 h / Heating 2.1: t-BuLi / tetrahydrofuran; pentane / 1 h / -78 °C 2.2: B(OMe)3 / tetrahydrofuran; pentane / 1 h / 0 °C 2.3: 84 percent / aq. TlOH / Pd(PPh3)4 / tetrahydrofuran; pentane / 3 h / 25 °C 3.1: 91 percent / aq. KOH / ethanol / 70 °C View Scheme

1.1: I2; DBN / diethyl ether / 15 h 1.2: 73 percent / DBN / benzene / 2.5 h / Heating 2.1: t-BuLi / tetrahydrofuran; pentane / 1 h / -78 °C 2.2: B(OMe)3 / tetrahydrofuran; pentane / 1 h / 0 °C 2.3: 84 percent / aq. TlOH / Pd(PPh3)4 / tetrahydrofuran; pentane / 3 h / 25 °C 3.1: 91 percent / aq. KOH / ethanol / 70 °C View Scheme