1: n-butyllithium / hexane; diethyl ether / 0.5 h / -70 °C 2: tetra-n-butylammonium fluoride / tetrahydrofuran / 0.17 h / 25 °C View Scheme

1,8-diazabicyclo[5.4.0]undec-7-ene in tetrahydrofuran 80 h; Ambient temperature;