1: 91 percent / (COCl)2, DMSO, TEA / CH2Cl2 2: 86 percent / KOt-Bu / tetrahydrofuran / 0.33 h / -78 deg C --> 0 deg C 3: 100 percent / DIBAL-H / CH2Cl2 / 0.25 h / -78 °C 4: 82 percent / NBS, PPh3, 2-methyl-2-butene / CH2Cl2 / 0.33 h / -78 deg C to 0 deg C 5: tetrahydrofuran / 0.33 h / 0 °C 6: NaIO4 / various solvent(s); H2O / 0 °C View Scheme

1: 4-hydroxymethyl-2-methyloxazole With n-butyllithium; lithium diethylamide in tetrahydrofuran; hexane T=-78°C; 2: methyl trifluoromethanesulfonate in tetrahydrofuran; hexane T=-78°C; Further stages.;

1: 1.) lithium diisopropylamide / 1) THF, -78 deg C, 20 min; 2) THF, -78 deg C, 1 h 2: 73 percent / oxalyl chloride, DMSO / CH2Cl2 / 0.75 h / -78 °C 3: diethyl ether / 1 h / Ambient temperature 4: 95 percent / oxalyl chloride, DMSO / CH2Cl2 / 1 h / -78 °C 5: 1.) hexamethyldisilazane, n-BuLi / 1) THF, -78 deg C, 45 min; 2) THF, hexane, -78 deg C, 2 h 6: 48 percent / PTSA / toluene / Heating 7: 1.) tert-butyldimethylsilyl trifluoromethanesulfonate, pyridine / 1) CH2Cl2, 30 min; 2) CH2Cl2, , 2 h View Scheme

carbon tetrabromide; triphenylphosphine in dichloromethane T=20°C; 4 h;

1: 76 percent / CBr4; PPh3 / CH2Cl2 / 4 h / 20 °C 2: 60 percent / benzene / 24 h / Heating View Scheme