2: 1. lithium diisopropylamine (LDA) / 1. THF, -50 deg C, 15min, 2. THF, 1h, -80 deg C 3: potassium t-butoxide (KOt-Bu) / tetrahydrofuran / -17 °C 4: tetrabutylammonium fluoride trihydrate (TBAF) / tetrahydrofuran / 1 h / 0 °C View Scheme

hydrogenchloride in tetrahydrofuran 4 h;