1: 50 percent / NaN3, PhI(OAc)2 / CH2Cl2 / 12 h / Ambient temperature 2: 75 percent / triphenylphosphine / benzene / 0.5 h / 50 °C 3: 90 percent / 35percent H2O2 / methanol / 1.) 0 deg C, 15 min, 2.) 40 deg C, 0.5 h View Scheme

lithium bromide in water; N,N-dimethyl-formamide T=195 - 200°C; 72 h;

1: 1)(NH4)2S2O8 2: H2O2 / methanol / 19 h / Ambient temperature 3: 10percent NaHCO3 / benzene / 6 h / Heating 4: 71 percent / amberlist / benzene / 4 h / Ambient temperature; other substit. 5-methylenefuran, -oxazole, or -thiazole derivatives; or isomerization reaction with 1,8-diazabicyclo<5.4.0>undec-7-ene at 50 deg C; different times View Scheme

[bmim]Br; 1,8-diazabicyclo[5.4.0]undec-7-ene T=25°C; 2 h;