1: 59 percent / 1.) butyllithium; 2.) 10percent hydrochloric acid / 1.) hexane/THF, RT, 0.5 h; 2.) reflux, 2 h 2: 41 percent / boron trifluoride etherate/molecular sieve 4A / toluene / 25 h / Heating 3: 72 percent / tetrahydrofuran / RT, 1h; 40 deg C, 1 h; reflux, 2 h 4: 72 percent / potassium hydroxide / ethane-1,2-diol / 6 h / Heating View Scheme

toluene-4-sulfonic acid in toluene 20 h; Heating / reflux;

1: 3-bromopropiophenone ethylene acetal With n-butyllithium in tetrahydrofuran T=-78°C; 0.5 h; 2: N,N-dimethyl-formamide in tetrahydrofuran T=-78 - 0°C; 3: With ammonium chloride; water in tetrahydrofuran