boron trifluoride diethyl etherate in dichloromethane T=23°C; 24 h;

1: 3-lt;(tert-butyldimethylsilyl)oxygt;-2-pyridone With n-butyllithium in tetrahydrofuran; hexane T=-78°C; 0.333333 h; 2: p-toluenesulfonyl chloride in tetrahydrofuran; hexane T=-78 - 20°C; 1 h;

1.1: MeLi / diethyl ether / 2 h / 0 °C 1.2: 82 percent / diethyl ether / 30 h / 23 °C 2.1: 98 percent / BF3*OEt2 / CH2Cl2 / 24 h / 23 °C View Scheme

1.1: 70 percent / 1H-imidazole / dimethylformamide / 23 °C 2.1: MeLi / diethyl ether / 2 h / 0 °C 2.2: 82 percent / diethyl ether / 30 h / 23 °C 3.1: 98 percent / BF3*OEt2 / CH2Cl2 / 24 h / 23 °C View Scheme

1.1: 1H-imidazole / N,N-dimethyl-formamide / 20 °C / Inert atmosphere 2.1: n-butyllithium / hexane; tetrahydrofuran / 0.33 h / -78 °C / Inert atmosphere 2.2: 1 h / -78 - 20 °C 3.1: hydrogenchloride; water / ethanol / 1 h View Scheme