PPA; Polyphosphoric acid (PPA) 1 h; Heating;

1: CuCl / diethyl ether / 3 h / ice-bath 2: aq.KOH / 3 h / Heating 3: 71 percent / aq.H2SO4 / 8 h / Heating 4: 55 percent / polyphosphoric acid (PPA) / 1 h / Heating View Scheme

1: 80 percent / piperidine 2: CuCl / diethyl ether / 3 h / ice-bath 3: aq.KOH / 3 h / Heating 4: 71 percent / aq.H2SO4 / 8 h / Heating 5: 55 percent / polyphosphoric acid (PPA) / 1 h / Heating View Scheme

1: 71 percent / aq.H2SO4 / 8 h / Heating 2: 55 percent / polyphosphoric acid (PPA) / 1 h / Heating View Scheme

(i) NaNH2, NaOtBu, THF, (ii) /BRN= 1236661/; Multistep reaction;