To a solution of S)-2-(2-bromo-6-methyl-4-nitrophenyl)-2-tert-butoxyethyl pivalate (9 g, 21.63 mmol) in EtOH (50 ml) and EtOAc (50 ml) was added Pt/C (1.5 g), attached with a balloon of H2. More Pt/C (500 mg) was added after 3 h. Then the reaction mixture was stirred at rt for another 2 h. The reaction mixture was filtered over celite, concentrated down to give product (S)-2-(4-amino-2-bromo-6-methylphenyl)-2-tert-butoxyethyl pivalate (65G) and went to next step without purification. To a solution of (S)-2-(4-amino-2-bromo-6-methylphenyl)-2-tert-butoxyethyl pivalate (65G) (21.63 mmol) in HOAc/THF (80 ml, 1:1) was added KSCN at 0° C. The reaction mixture was stirred at 0° C. for 0.5 h. Then Br2 was added slowly, reacted at 0° C. The reaction was quenched by adding sat. NaHSO3, extracted by EtOAc, dried over MgSO4, purified by silica gel column, eluting by 0-40% EtOAc in Hexanes to give 65H (2.3 g, 24% over 2 steps).
