lithium diethylamide 1) THF, a) -70 deg C, b) 0 deg C, 30 min, 2) THF, a) -70 deg C, b) r.t., 2 h; Yield given. Multistep reaction. Yields of byproduct given;

oxonium; lithium diethylamide 1) THF, a) -70 deg C, b) 0 deg C, 30 min, 2) THF, a) -70 deg C, b) r.t., 2 h; with but-2-enoic acid; Mechanism;