1: 56 percent / LICA / tetrahydrofuran / -78 deg C to 20 deg C 2: 94 percent / K2CO3 / acetone 3: 1.) LICA / 1.) THF, 0 deg C, 2.) 0 deg C 4: 1.) KOH, 2.) aq. oxalic acid, silicagel / 1.) MeOH, 2.) CH2Cl2, 20 deg C 5: 1.) O3, 2.) CF3COOH / 1.) MeOH, -78 deg C, 2.) CHCl3, H2O View Scheme

1: 63 percent / Et2NH, n-BuLi / tetrahydrofuran; hexane / 1.) -78 deg C, 4 h, 2.) RT, 4 d 2: 1.) LDA / 1.) THF, hexane, from -78 to 50 deg C, 2.5 h, 2.) THF, hexane, RT, 1 h 3: 1.) O3/O2, 2.) BHT, 15percent aq. H2SO4, silica gel / 1.) CH2Cl2, -78 deg C, 2 min, 2.) CH2Cl2, 22 deg C, overnight View Scheme

Multi-step reaction with 2 steps 1: 1.) n-BuLi, TMEDA, 2.) DMF2: 1.) Et2O, pentane, -78 deg C, 2.) DMAP, 20 deg C  

With  n-butyllithium; diethylamine in  tetrahydrofuran; hexane  1.) -78 deg C, 4 h, 2.) RT, 4 d;   

Multi-step reaction with 4 steps 1: 56 percent / LICA / tetrahydrofuran / -78 deg C to 20 deg C2: 94 percent / K2CO3 / acetone3: 1.) LICA / 1.) THF, 0 deg C, 2.) 0 deg C4: 1.) KOH, 2.) aq. oxalic acid, silicagel / 1.) MeOH, 2.) CH2Cl2, 20 deg C  

Multi-step reaction with 2 steps 1: 56 percent / LICA / tetrahydrofuran / -78 deg C to 20 deg C2: 94 percent / K2CO3 / acetone  

Multi-step reaction with 2 steps 1: 63 percent / Et2NH, n-BuLi / tetrahydrofuran; hexane / 1.) -78 deg C, 4 h, 2.) RT, 4 d2: 1.) LDA / 1.) THF, hexane, from -78 to 50 deg C, 2.5 h, 2.) THF, hexane, RT, 1 h