boron trifluoride diethyl etherate in methanol T=25°C; 15 h;

n-butyllithium; potassium tert-butylate in tetrahydrofuran; hexane T=-75°C; 2 h;

1: 65 percent / N-ethyldiisopropylamine / CH2Cl2 / 2 h / 25 °C 2: 54 percent / potassium tert-butoxide; butyllithium / tetrahydrofuran; hexane / 2 h / -75 °C View Scheme