1: 81 percent / tetrahydrofuran / 1.) 0 deg C, 30 min; 2.) rt, 4.5 h 2: 82 percent / aq. HCl; tetrahydrofuran / 72 h / Ambient temperature 3: 74 percent / pyridine 4: N-bromosuccinimide / CCl4 / 0.33 h / Heating 5: tetra-n-butylammonium fluoride / tetra-n-butylammonium bromide / tetrahydrofuran 6: potassium hydroxide / tetrahydrofuran; methanol View Scheme

Multi-step reaction with 4 steps 1: 73 percent / pyridine / 0.5 h / 0 °C2: 85 percent / dimethylsulfoxide / 4 h / 90 - 100 °C3: potassium hydroxide / H2O; ethanol / 2 h / Heating4: methanol; diethyl ether / 1 h / Ambient temperature  

Multi-step reaction with 7 steps 1: lithium / liquid ammonia; tetrahydrofuran / 1.5 h / -78 °C2: N,N-diethylcyclohexylamine / dioxane / 1.) 50 deg C, 6 h; 2.) 80 deg C, 2 h3: aq. HCl; tetrahydrofuran; methanol / Ambient temperature4: 73 percent / pyridine / 0.5 h / 0 °C5: 85 percent / dimethylsulfoxide / 4 h / 90 - 100 °C6: potassium hydroxide / H2O; ethanol / 2 h / Heating7: methanol; diethyl ether / 1 h / Ambient temperature  

Multi-step reaction with 5 steps 1: aq. HCl; tetrahydrofuran; methanol / Ambient temperature2: 73 percent / pyridine / 0.5 h / 0 °C3: 85 percent / dimethylsulfoxide / 4 h / 90 - 100 °C4: potassium hydroxide / H2O; ethanol / 2 h / Heating5: methanol; diethyl ether / 1 h / Ambient temperature  

Multi-step reaction with 3 steps 1: 81 percent / tetrahydrofuran / 1.) 0 deg C, 30 min; 2.) rt, 4.5 h2: 82 percent / aq. HCl; tetrahydrofuran / 72 h / Ambient temperature3: 74 percent / pyridine  

 in  tetrahydrofuran  1.) 0 deg C, 30 min; 2.) rt, 4.5 h;