1: 1) (COCl)2, DMSO, 2) NEt3 / 1a) CH2Cl2, -78 deg C, 15 min, 1b) -45 deg C, 1 h, 2a) -45 deg C, 20 min, 2b) 0 deg C, 15 min 2: 78 percent / p-TsOH*H2O / 14 h / Ambient temperature 3: 1) 60percent HOAc, 2) NaBH3CN, HOAc / 1) RT, 3 d, 2) EtOH, RT, 1 h 4: 0.5 N NaOH / tetrahydrofuran / 19 h / 0 °C 5: CF3COOH / CH2Cl2 / 0.25 h / Ambient temperature View Scheme

1: 1) (COCl)2, DMSO, 2) NEt3 / 1a) CH2Cl2, -78 deg C, 15 min, 1b) -45 deg C, 1 h, 2a) -45 deg C, 20 min, 2b) 0 deg C, 15 min 2: 78 percent / p-TsOH*H2O / 14 h / Ambient temperature 3: 1) 60percent HOAc, 2) NaBH3CN, HOAc / 1) RT, 3 d, 2) EtOH, RT, 1 h View Scheme

1: 1) (COCl)2, DMSO, 2) NEt3 / 1a) CH2Cl2, -78 deg C, 15 min, 1b) -45 deg C, 1 h, 2a) -45 deg C, 20 min, 2b) 0 deg C, 15 min 2: 78 percent / p-TsOH*H2O / 14 h / Ambient temperature 3: 1) 60percent HOAc, 2) NaBH3CN, HOAc / 1) RT, 3 d, 2) EtOH, RT, 1 h 4: 0.5 N NaOH / tetrahydrofuran / 19 h / 0 °C View Scheme

With  sodium hydroxide; camphor-10-sulfonic acid  1) water, 0 deg C, 14 h, 2) CH2Cl2, RT, 20 h;  Yield given. Multistep reaction;   

Multi-step reaction with 2 steps 1: 100 percent / K2CO3 / 0.5 h / 0 °C2: 1) 0.5 N NaOH, 2) dl-10-camphorsulfonic acid / 1) THF, 0 deg C, 14 h, 2) CH2Cl2, RT, 20 h