Scheme 4. Reagents and Reaction conditions:
a) appropriate ester of 4,4,4-trifluoro-3-methylbutanoic acid, HMDS, n-BuLi, THF, −78 °C, 2.5 h, 70% for 110, 25% for 112; b) TFA, CH2Cl2, 20 °C, 16 h, 68%; c) LiCl, DMSO, 130 °C (microwave irradiation), 3 h, 76%.