1: 56 percent / sodium formate / 1) 70-75 deg C, 3 h, 2) room temp., 1 h 2: 1) THF, -78 - 0 deg C, 2) CDCl3, 140 deg C, 1 h View Scheme

With  3-chloro-benzenecarboperoxoic acid in  dichloromethane T=0°C; 5 h;   

Multi-step reaction with 3 steps 1: 84 percent / K2CO3 / acetone / 48 h / Heating2: 1) diisopropylamine, n-BuLi3: 81 percent / triphenylcarbenium tetrafluoroborate / CH2Cl2 / 1) 0 deg C, 2 h, 2) room temp., 0.5 h