1.1: n-BuLi / tetrahydrofuran; hexane / 0.5 h / -78 °C 1.2: 57 percent / tetrahydrofuran; hexane / 2 h / -78 °C 2.1: 77 percent / AlCl3 / CH2Cl2 / 4 h / 20 °C View Scheme

1: 5-bromo-6-methoxy-2,2-dimethyl-2H-naphtho[1,2-b]pyran With n-butyllithium in tetrahydrofuran; hexane T=-78°C; 0.5 h; 2: methyl chloroformate in tetrahydrofuran; hexane T=-78°C; 2 h;