To a stirred solution of 3-(1-(4-fluorophenyl)-1H-indazol-5-yl)-2,2-dimethyl-3-phenylpropan-1-ol (1.3 g, 3.5 mmol) in CH2Cl2 (150 mL) was added Dess-Martin periodinane (2.12 g, 5.0 mmol) portionwise at RT under nitrogen. After stirring at RT for 24 hr, the mixture was poured into a 1N sodium hydroxide solution (100 mL), extracted with CH2Cl2 (100 mL), dried (Na2SO4) and concentrated. The crude residue was purified over silica gel eluting with EtOAc/hexanes (1:3) to give 1.03 g (79% yield) of 3-(1-(4-fluorophenyl)-1H-indazol-5-yl)-2,2-dimethyl-3-phenylpropanal, the NMR spectrum of which was consistent with the desired structure.
