1: 1.) LICA / 1.) THF, 0 deg C, 2.) 0 deg C 2: 1.) KOH, 2.) aq. oxalic acid, silicagel / 1.) MeOH, 2.) CH2Cl2, 20 deg C 3: 1.) O3, 2.) CF3COOH / 1.) MeOH, -78 deg C, 2.) CHCl3, H2O View Scheme

Multi-step reaction with 2 steps 1: 1.) LICA / 1.) THF, 0 deg C, 2.) 0 deg C2: 1.) KOH, 2.) aq. oxalic acid, silicagel / 1.) MeOH, 2.) CH2Cl2, 20 deg C  

Multi-step reaction with 3 steps 1: 1.) Et2O, pentane, -78 deg C, 2.) DMAP, 20 deg C2: 56 percent / LICA / tetrahydrofuran / -78 deg C to 20 deg C3: 94 percent / K2CO3 / acetone  

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 4 steps 1: 1.) n-BuLi, TMEDA, 2.) DMF2: 1.) Et2O, pentane, -78 deg C, 2.) DMAP, 20 deg C3: 56 percent / LICA / tetrahydrofuran / -78 deg C to 20 deg C4: 94 percent / K2CO3 / acetone