1: 35 percent / K2CO3, 18-crown-6 / toluene / 80 °C 2: H2O / PPTS / tetrahydrofuran / 1.5 h / Heating 3: PCC, sodium acetate / CH2Cl2 / 2.5 h 4: 1.) LDA, 1,10-phenanthroline / 1.) THF, -78 deg C, 15 min; 2.) THF, -20 deg C, 5 min. 5: 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide metho-p-toluenesulphonate / copper(II) iodide / acetonitrile / 4 h / 55 - 58 °C 6: 90 percent / KOH / aq. ethanol / 3 h / Heating View Scheme

1: 35 percent / K2CO3, 18-crown-6 / toluene / 80 °C 2: H2O / PPTS / tetrahydrofuran / 1.5 h / Heating 3: PCC, sodium acetate / CH2Cl2 / 2.5 h 4: 1.) LDA, 1,10-phenanthroline / 1.) THF, -78 deg C, 15 min; 2.) THF, -20 deg C, 5 min. 5: 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide metho-p-toluenesulphonate / copper(II) iodide / acetonitrile / 4 h / 55 - 58 °C 6: 90 percent / KOH / aq. ethanol / 3 h / Heating View Scheme

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

Multi-step reaction with 9 steps 1: 1.) sodium hydride / 1.) DME, RT, 10 min; 2.) DME, RT, overnight2: 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 h3: LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C / Heating4: PPTS / CH2Cl2 / 0.08 h / Ambient temperature5: 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.6: 90 percent / triphenylphosphine, imidazole, I2 / tetrahydrofuran; acetonitrile / 0.5 h / -10 °C7: 1.) NaH / 1.) DMSO, RT, 30 min; 2.) DMSO, overnight8: MeOH / PPTS / 0.08 h / Heating9: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C  

Multi-step reaction with 11 steps 1: DMAP2: K2CO3 / methanol3: MnO2 / (COCl)2, DMSO and Et3N4: 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 h5: LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C / Heating6: PPTS / CH2Cl2 / 0.08 h / Ambient temperature7: 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.8: 90 percent / triphenylphosphine, imidazole, I2 / tetrahydrofuran; acetonitrile / 0.5 h / -10 °C9: 1.) NaH / 1.) DMSO, RT, 30 min; 2.) DMSO, overnight10: MeOH / PPTS / 0.08 h / Heating11: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C  

Multi-step reaction with 10 steps 1: 86 percent / DIBAH / CH2Cl2; hexane / 0.17 h / -78 °C2: 1.) sodium hydride / 1.) DME, RT, 10 min; 2.) DME, RT, overnight3: 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 h4: LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C / Heating5: PPTS / CH2Cl2 / 0.08 h / Ambient temperature6: 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.7: 90 percent / triphenylphosphine, imidazole, I2 / tetrahydrofuran; acetonitrile / 0.5 h / -10 °C8: 1.) NaH / 1.) DMSO, RT, 30 min; 2.) DMSO, overnight9: MeOH / PPTS / 0.08 h / Heating10: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C  

Multi-step reaction with 11 steps 1: 2.) acetyl chloride / 1.) THF, -10 deg C, 30 min; 2.) -10 deg C, 5 min.2: 86 percent / DIBAH / CH2Cl2; hexane / 0.17 h / -78 °C3: 1.) sodium hydride / 1.) DME, RT, 10 min; 2.) DME, RT, overnight4: 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 h5: LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C / Heating6: PPTS / CH2Cl2 / 0.08 h / Ambient temperature7: 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.8: 90 percent / triphenylphosphine, imidazole, I2 / tetrahydrofuran; acetonitrile / 0.5 h / -10 °C9: 1.) NaH / 1.) DMSO, RT, 30 min; 2.) DMSO, overnight10: MeOH / PPTS / 0.08 h / Heating11: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C  

Multi-step reaction with 12 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.9: 90 percent / triphenylphosphine, imidazole, I2 / tetrahydrofuran; acetonitrile / 0.5 h / -10 °C10: 1.) NaH / 1.) DMSO, RT, 30 min; 2.) DMSO, overnight11: MeOH / PPTS / 0.08 h / Heating12: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C  

Multi-step reaction with 13 steps 1: 100 percent / K2CO3 / methanol / -20 °C2: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C3: 2.) acetyl chloride / 1.) THF, -10 deg C, 30 min; 2.) -10 deg C, 5 min.4: 86 percent / DIBAH / CH2Cl2; hexane / 0.17 h / -78 °C5: 1.) sodium hydride / 1.) DME, RT, 10 min; 2.) DME, RT, overnight6: 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 h7: LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C / Heating8: PPTS / CH2Cl2 / 0.08 h / Ambient temperature9: 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.10: 90 percent / triphenylphosphine, imidazole, I2 / tetrahydrofuran; acetonitrile / 0.5 h / -10 °C11: 1.) NaH / 1.) DMSO, RT, 30 min; 2.) DMSO, overnight12: MeOH / PPTS / 0.08 h / Heating13: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C  

Multi-step reaction with 8 steps 1: 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 h2: LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C / Heating3: PPTS / CH2Cl2 / 0.08 h / Ambient temperature4: 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.5: 90 percent / triphenylphosphine, imidazole, I2 / tetrahydrofuran; acetonitrile / 0.5 h / -10 °C6: 1.) NaH / 1.) DMSO, RT, 30 min; 2.) DMSO, overnight7: MeOH / PPTS / 0.08 h / Heating8: 1.) DMSO, (COCl)2 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min; 2.) CH2Cl2, -78 to 0 deg C