1: 1.) diisopropylamine, n-butyllithium / 1.) hexane, diethyl ether, -10 deg C, 30 min; 2.) diethyl ether, -78 deg C, 2 h; room temp., 12 h 2: oxalic acid / H2O / 24 h / Ambient temperature View Scheme

1: 1.) diisopropylamine, n-butyllithium / 1.) hexane, diethyl ether, -10 deg C, 30 min; 2.) diethyl ether, -78 deg C, 2 h; room temp., 12 h 2: oxalic acid / H2O / 24 h / Ambient temperature View Scheme