1: With n-butyllithium in diethyl ether; hexane T=-75°C; 1 h; 2: With tri-isopropoxy-borane in diethyl ether; hexane T=20°C; 2.5 h; 3: With hydrogenchloride in diethyl ether; hexane 1.5 h; Heating; Further stages.;

1.1: 89 percent / p-toluenesulfonic acid / toluene / 15 h / Heating 2.1: n-BuLi / diethyl ether; hexane / 0.75 h / -78 °C 2.2: B(OBu)3 / -78 - 20 °C 2.3: 81 percent / H2O; H+ / 2 h / 25 °C View Scheme

1: With n-butyllithium in tetrahydrofuran T=-78°C; 0.5 h; 2: With boric acid trimethyl ester in tetrahydrofuran T=-78 - 20°C; 3: With hydrogenchloride; water in tetrahydrofuran T=20°C;

hydrogenchloride; n-butyllithium in diethyl ether; hexane (N2); addn. of a soln. of BuLi in hexane to a soln. of acetal in ether at -75°C, stirring for 1 h, addn. of boron compd., stirring at room temp. for 2.5 h, addn. of aq. HCl, refluxing for 1.5 h with stirring; sepn. of ppt., extn. with aq. NaOH, acidification of the ext.;

1: bromine / dichloromethane 2: APTS / benzene 3: n-butyllithium / tetrahydrofuran 4: hydrogenchloride; water View Scheme

1.1: N-bromosuccinmide; 2,2'-azo-bisisobutyronitrile / tetrachloromethane / 6 h / Reflux; UV-irradiation 2.1: water; calcium carbonate / 16 h / Reflux 3.1: tetra-n-butylammonium tribromide; orthoformic acid triethyl ester / 12 h / 65 °C 4.1: n-butyllithium / tetrahydrofuran / 0.5 h / -78 °C 4.2: -78 - 20 °C 4.3: 20 °C View Scheme

1.1: water; calcium carbonate / 16 h / Reflux 2.1: tetra-n-butylammonium tribromide; orthoformic acid triethyl ester / 12 h / 65 °C 3.1: n-butyllithium / tetrahydrofuran / 0.5 h / -78 °C 3.2: -78 - 20 °C 3.3: 20 °C View Scheme

sodium tetrahydroborate in methanol T=20°C; 2 h;

potassium permanganate; sodium hydroxide in water T=23°C; 4 h;

1: bis-triphenylphosphine-palladium(II) chloride; potassium carbonate / ethylene glycol dimethyl ether; water / 1 h / 70 °C 2: caesium carbonate / N,N-dimethyl-formamide / 60 °C 3: water; lithium hydroxide hydrate / tetrahydrofuran; methanol / 20 °C 4: O-(1H-benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate; N-ethyl-N,N-diisopropylamine / tetrahydrofuran 5: sulphonic acid amide / 1,2-dioxacyclohexane / 100 °C 6: trifluoroacetic acid / dichloromethane 7: tetrahydrofuran / 20 °C 8: 1,8-diazabicyclo[5.4.0]undec-7-ene / tetrahydrofuran View Scheme