1: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C 2: 2.) acetyl chloride / 1.) THF, -10 deg C, 30 min; 2.) -10 deg C, 5 min. 3: 86 percent / DIBAH / CH2Cl2; hexane / 0.17 h / -78 °C 4: 1.) sodium hydride / 1.) DME, RT, 10 min; 2.) DME, RT, overnight 5: 1.) TMEDA, n-BuLi 2.) ClTi(O-iPr)3 / 1.) ether, hexane, -78 deg C, 1 h 2.) ether, hexane, -78 deg C, 2 h then -10 deg C, 1.5 h 6: LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C / Heating 7: PPTS / CH2Cl2 / 0.08 h / Ambient temperature 8: 1.) B2H6, 2-methyl-2-butene 3.) 3M NaOH, 30percent aq. H2O2 / 1.) THF, -10 deg C, 2 h 2.) THF, 0 deg C, 30 min; 3.) THF, RT, 30 min. 9: 90 percent / triphenylphosphine, imidazole, I2 / tetrahydrofuran; acetonitrile / 0.5 h / -10 °C 10: 1.) NaH / 1.) DMSO, RT, 30 min; 2.) DMSO, overnight 11: MeOH / PPTS / 0.08 h / Heating 12: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C 13: 35 percent / K2CO3, 18-crown-6 / toluene / 80 °C 14: H2O / PPTS / tetrahydrofuran / 1.5 h / Heating 15: PCC, sodium acetate / CH2Cl2 / 2.5 h 16: 1.) LDA, 1,10-phenanthroline / 1.) THF, -78 deg C, 15 min; 2.) THF, -20 deg C, 5 min. 17: 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide metho-p-toluenesulphonate / copper(II) iodide / acetonitrile / 4 h / 55 - 58 °C 18: 90 percent / KOH / aq. ethanol / 3 h / Heating View Scheme

1: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C 2: 2.) acetyl chloride / 1.) THF, -10 deg C, 30 min; 2.) -10 deg C, 5 min. 3: 86 percent / DIBAH / CH2Cl2; hexane / 0.17 h / -78 °C 4: 1.) sodium hydride / 1.) DME, RT, 10 min; 2.) DME, RT, overnight 5: 1.) TMEDA, n-BuLi 2.) ClTi(O-iPr)3 / 1.) ether, hexane, -78 deg C, 1 h 2.) ether, hexane, -78 deg C, 2 h then -10 deg C, 1.5 h 6: LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C / Heating 7: PPTS / CH2Cl2 / 0.08 h / Ambient temperature 8: 1.) B2H6, 2-methyl-2-butene 3.) 3M NaOH, 30percent aq. H2O2 / 1.) THF, -10 deg C, 2 h 2.) THF, 0 deg C, 30 min; 3.) THF, RT, 30 min. 9: 90 percent / triphenylphosphine, imidazole, I2 / tetrahydrofuran; acetonitrile / 0.5 h / -10 °C 10: 1.) NaH / 1.) DMSO, RT, 30 min; 2.) DMSO, overnight 11: MeOH / PPTS / 0.08 h / Heating 12: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C 13: 35 percent / K2CO3, 18-crown-6 / toluene / 80 °C 14: H2O / PPTS / tetrahydrofuran / 1.5 h / Heating 15: PCC, sodium acetate / CH2Cl2 / 2.5 h 16: 1.) LDA, 1,10-phenanthroline / 1.) THF, -78 deg C, 15 min; 2.) THF, -20 deg C, 5 min. 17: 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide metho-p-toluenesulphonate / copper(II) iodide / acetonitrile / 4 h / 55 - 58 °C 18: 90 percent / KOH / aq. ethanol / 3 h / Heating View Scheme

With  potassium carbonate in  methanol T=-20°C;   

With  oxalyl dichloride; dimethyl sulfoxide; triethylamine in  dichloromethane T=-78°C;  Yield given;   

Multi-step reaction with 3 steps 1: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C2: 2.) acetyl chloride / 1.) THF, -10 deg C, 30 min; 2.) -10 deg C, 5 min.3: 86 percent / DIBAH / CH2Cl2; hexane / 0.17 h / -78 °C  

Multi-step reaction with 2 steps 1: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C2: 2.) acetyl chloride / 1.) THF, -10 deg C, 30 min; 2.) -10 deg C, 5 min.  

Multi-step reaction with 4 steps 1: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C2: 2.) acetyl chloride / 1.) THF, -10 deg C, 30 min; 2.) -10 deg C, 5 min.3: 86 percent / DIBAH / CH2Cl2; hexane / 0.17 h / -78 °C4: 1.) sodium hydride / 1.) DME, RT, 10 min; 2.) DME, RT, overnight  

Multi-step reaction with 6 steps 1: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C2: 2.) acetyl chloride / 1.) THF, -10 deg C, 30 min; 2.) -10 deg C, 5 min.3: 86 percent / DIBAH / CH2Cl2; hexane / 0.17 h / -78 °C4: 1.) sodium hydride / 1.) DME, RT, 10 min; 2.) DME, RT, overnight5: 1.) TMEDA, n-BuLi 2.) ClTi(O-iPr)3 / 1.) ether, hexane, -78 deg C, 1 h 2.) ether, hexane, -78 deg C, 2 h then -10 deg C, 1.5 h6: LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C / Heating  

Multi-step reaction with 7 steps 1: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C2: 2.) acetyl chloride / 1.) THF, -10 deg C, 30 min; 2.) -10 deg C, 5 min.3: 86 percent / DIBAH / CH2Cl2; hexane / 0.17 h / -78 °C4: 1.) sodium hydride / 1.) DME, RT, 10 min; 2.) DME, RT, overnight5: 1.) TMEDA, n-BuLi 2.) ClTi(O-iPr)3 / 1.) ether, hexane, -78 deg C, 1 h 2.) ether, hexane, -78 deg C, 2 h then -10 deg C, 1.5 h6: LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C / Heating7: PPTS / CH2Cl2 / 0.08 h / Ambient temperature  

Multi-step reaction with 8 steps 1: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C2: 2.) acetyl chloride / 1.) THF, -10 deg C, 30 min; 2.) -10 deg C, 5 min.3: 86 percent / DIBAH / CH2Cl2; hexane / 0.17 h / -78 °C4: 1.) sodium hydride / 1.) DME, RT, 10 min; 2.) DME, RT, overnight5: 1.) TMEDA, n-BuLi 2.) ClTi(O-iPr)3 / 1.) ether, hexane, -78 deg C, 1 h 2.) ether, hexane, -78 deg C, 2 h then -10 deg C, 1.5 h6: LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C / Heating7: PPTS / CH2Cl2 / 0.08 h / Ambient temperature8: 1.) B2H6, 2-methyl-2-butene 3.) 3M NaOH, 30percent aq. H2O2 / 1.) THF, -10 deg C, 2 h 2.) THF, 0 deg C, 30 min; 3.) THF, RT, 30 min.