toluene-4-sulfonic acid in tetrahydrofuran; acetonitrile T=0 - 20°C;

1.1: BuLi; N,N,N',N'-tetramethylethylenediamine / hexane; diethyl ether / 20 °C 1.2: 61 percent / hexane; diethyl ether / 5.5 h / 0 - 20 °C 2.1: 81 percent / p-toluenesulfonic acid monohydrate / acetonitrile; tetrahydrofuran / 0 - 20 °C View Scheme

1: 95 percent / Mg / tetrahydrofuran / 14 h / Heating 2: 50 percent / Et3SiH / acetic acid / 12 h / 80 °C View Scheme