1: CH2Cl2 / 6 h / Heating 2: 76 percent / DIBAL-H / toluene; hexane / 0.5 h / -78 °C 3: Et3N, SO3-C5H5N, DMSO / Ambient temperature 4: CH2Cl2 / 24 h / Heating 5: aq. LiOH / methanol / 12 h / 45 °C 6: 88 percent / DDQ / dioxane / 0.08 h / Ambient temperature 7: Et3N, ClCOOEt / tetrahydrofuran / 0.08 h / 0 °C 8: Amberlyst 15 / methanol / 1 h / 45 °C View Scheme

Multi-step reaction with 3 steps 1: 90 percent / PPTS / 3 h / Ambient temperature2: 80 percent / (n-Bu)4NF / tetrahydrofuran / 4 h / 40 °C3: Et3N, SO3-C5H5N, DMSO / Ambient temperature  

Multi-step reaction with 2 steps 1: 80 percent / (n-Bu)4NF / tetrahydrofuran / 4 h / 40 °C2: Et3N, SO3-C5H5N, DMSO / Ambient temperature  

Multi-step reaction with 7 steps 1: CH2Cl2 / 6 h / Heating2: 76 percent / DIBAL-H / toluene; hexane / 0.5 h / -78 °C3: Et3N, SO3-C5H5N, DMSO / Ambient temperature4: CH2Cl2 / 24 h / Heating5: aq. LiOH / methanol / 12 h / 45 °C6: 88 percent / DDQ / dioxane / 0.08 h / Ambient temperature7: Et3N, ClCOOEt / tetrahydrofuran / 0.08 h / 0 °C  

Multi-step reaction with 8 steps 1: CH2Cl2 / 6 h / Heating2: 76 percent / DIBAL-H / toluene; hexane / 0.5 h / -78 °C3: Et3N, SO3-C5H5N, DMSO / Ambient temperature4: CH2Cl2 / 24 h / Heating5: aq. LiOH / methanol / 12 h / 45 °C6: 88 percent / DDQ / dioxane / 0.08 h / Ambient temperature7: Et3N, ClCOOEt / tetrahydrofuran / 0.08 h / 0 °C8: Amberlyst 15 / methanol / 1 h / 45 °C