1: 1H-imidazole / N,N-dimethyl-formamide / 0.75 h / 20 °C 2: triphenylphosphine hydrobromide / chloroform / 3.17 h / 20 °C / |Molecular sieve 3: ammonium fluoride-hydrogen fluoride / N,N-dimethyl-formamide; 1-methyl-pyrrolidin-2-one / 4 h / 70 °C View Scheme