1: (E)-N-(2,2-dimethyl-5-phenylpent-4-yn-1-ylidene)benzylamine With KDMO in tetrahydrofuran T=0°C; 1 h; 2: oxalic acid With water in toluene 0.5 h; Reflux; 3: With silver tetrafluoroborate in dichloromethane T=40°C; 6 h;