1: (CH3)2SO, pyridine, CF3COOH, dicyclohexylcarbodiimide (DCC) / benzene / 0.5 h / Ambient temperature 2: benzene; diethyl ether / 0.33 h 3: n-Bu4NF / tetrahydrofuran / 0.25 h / 0 °C 4: 75percent aq. CH3COOH / tetrahydrofuran / 0 - 5 °C 5: 68 percent / diethyl cyanophosphonate, Et3N / dimethylformamide / 0.5 h / 0 °C 6: 86 percent / (COCl)2, (CH3)2SO / CH2Cl2 / 0.33 h / -78 °C 7: 69 percent / lithium bis(trimethylsilyl)amide / tetrahydrofuran / 2.5 h / 0 °C 8: 100 percent / 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), H2O / CH2Cl2 / 0.5 h / Ambient temperature 9: 64 percent / CF3COOH / 2.5 h / Ambient temperature View Scheme

<b>Multi-step reaction with 10 steps<br /> </b>1: 2.) phenyllithium, 3.) t-BuOK<br />2: 96 percent / CH₃COOH, H₂O / tetrahydrofuran / 1 h / Ambient temperature<br />3: 80 percent / pyridine / 48 h / Ambient temperature<br />4: 97 percent / NaH, 18-crown-6 / tetrahydrofuran / 3 h<br />5: 1.) n-butyllithium / 1.) THF, hexane, -23 deg C, 80 min, 2.) THF, hexane, 5 min<br />6: 1.) KH, 2.) tetrabutylammonium chloride, 18-crown-6 / 1.) THF, 15 min, 2.) THF, RT, 20 min<br />7: 86 percent / sodium naphthalenide / 1,2-dimethoxy-ethane / 0.67 h / -78 &deg;C<br />8: 99 percent / K₂CO₃ / tetrahydrofuran; toluene<br />9: 85 percent / MeI, H₂O / acetonitrile / Ambient temperature<br />10: 1.) t-BuLi, 2.) dineopentylzinc<br /> <br /> &nbsp;

<b>Multi-step reaction with 8 steps<br /> </b>1: diisobutylaluminum hydride (DIBAL) / CH₂Cl₂; hexane / 0.5 h / -78 &deg;C<br />2: 1.) lithium diisopropylamide (LDA) / 1.) THF, 0 deg C, 10 min, 2.) THF, hexane, 0 deg C, 1 h<br />3: 1.) n-butyllithium / 1.) THF, hexane, -23 deg C, 80 min, 2.) THF, hexane, 5 min<br />4: 1.) KH, 2.) tetrabutylammonium chloride, 18-crown-6 / 1.) THF, 15 min, 2.) THF, RT, 20 min<br />5: 86 percent / sodium naphthalenide / 1,2-dimethoxy-ethane / 0.67 h / -78 &deg;C<br />6: 99 percent / K₂CO₃ / tetrahydrofuran; toluene<br />7: 85 percent / MeI, H₂O / acetonitrile / Ambient temperature<br />8: 1.) t-BuLi, 2.) dineopentylzinc<br /> <br /> &nbsp;

<b>Multi-step reaction with 6 steps<br /> </b>1: p-toluenesulfonic acid (PTSA) / 1.) reflux, 2.5 h, 2.) RT, 16 h<br />2: 1.) n-BuLi / 1.) THF, hexane, from 20 deg C to 0 deg C, 10 min, 2.) THF, hexane, 0.5 h<br />3: 98 percent / toluene / 8 h / Heating<br />4: diisobutylaluminum hydride (DIBAL) / CH₂Cl₂; hexane / 0.5 h / -78 &deg;C<br />5: 1 M aq. HCl / diethyl ether / 1 h<br />6: 1.) t-BuLi, 2.) dineopentylzinc<br /> <br /> &nbsp;

<b>Multi-step reaction with 2 steps<br /> </b>1: 90 percent / Et₃N, 4-(dimethylamino)pyridine / CH₂Cl₂ / 2 h / Ambient temperature<br />2: 1.) t-BuLi, 2.) dineopentylzinc<br /> <br /> &nbsp;