1: 94 percent / HBr / aq. acetic acid; benzene / 2 h / Ambient temperature 2: 82 percent / dimethyl sulfoxide / 2 h / Ambient temperature 3: NaOH, methyllithium View Scheme

1: 94 percent / HBr / aq. acetic acid; benzene / 2 h / Ambient temperature 2: 82 percent / dimethyl sulfoxide / 2 h / Ambient temperature 3: NaOH, methyllithium 4: chromic acid View Scheme