1: With n-butyllithium in tetrahydrofuran 2: With boric acid trimethyl ester in tetrahydrofuran 3: With peracetic acid in tetrahydrofuran

1: 1.) PhLi, trimethyl borate, 2.) peracetic acid / 1.) THF, -40 deg C, 1 h; -70 deg C, 2 h 2: 77 percent / NaOMe / dimethylformamide / 1.5 h / Ambient temperature 3: 75 percent 4: 1.) n-BuLi, trimethylborate, 2.) peracetic acid / 1.) THF, 0 deg C, 1 h; -70 deg C, 2 h, 2.) aq. acetic acid, -70 deg C to r.t. View Scheme

1: 77 percent / NaOMe / dimethylformamide / 1.5 h / Ambient temperature 2: 75 percent 3: 1.) n-BuLi, trimethylborate, 2.) peracetic acid / 1.) THF, 0 deg C, 1 h; -70 deg C, 2 h, 2.) aq. acetic acid, -70 deg C to r.t. View Scheme

1: 75 percent 2: 1.) n-BuLi, trimethylborate, 2.) peracetic acid / 1.) THF, 0 deg C, 1 h; -70 deg C, 2 h, 2.) aq. acetic acid, -70 deg C to r.t. View Scheme