1: 45 percent / N,N'-dicyclohexylcarbodiimide, 4-pyrrolidinopyridine / acetonitrile / 20 h / Ambient temperature 2: 22 percent / triethylsilane, BF3*Et2O / 48 h / Ambient temperature 3: Ba(OH)2 / methanol; H2O / 6 h / Heating View Scheme