racemic (2'R,3R,4'S)-6-bromo-4'-(3-chlorophenyl)-1'-(2,3-dihydroxy-propyl)-2'-(1-methyl cyclopropyl)-2,3-dihydro-2,6'-dioxospiro[indole-3,3'-piperidine] 1-methoxyethyl trimethylsilane → racemic (2'R,3R,4'S)-6-bromo-4'-(3-chlorophenyl)-1'-(2,3-dihydroxy-propyl)-2'-(1-methylcyclopropyl)-spiro[3H-indole-3,3'-piperidine]-2,6'(1H)-dione

The compound racemic (2′R,3R,4′S)-6-bromo-4′-(3-chlorophenyl)-1′-(2,3-dihydroxy-propyl)-2′-(1-methyl cyclopropyl)-2,3-dihydro-2,6′-dioxospiro[indole-3,3′-piperidine]-1-methoxyethyl trimethylsilane (40 mg, 0.06 mmol) was dissolved in trifluoroacetic acid (3 mL). The solution was stirred at room temperature for 1 h, then concentrated. The residue was dissolved in a solution of methanol (3 mL) and N,N′-diisopropylethylamine (1 mL). The reaction tube was then placed into the cavity of a focused monomode microwave reactor and the contents of the flask were irradiated at 120° C. for 30 min. The reaction mixture was concentrated and the residue was purified by Prep-HPLC to give title compound (20 mg, 63%) m/z (M+H)+: 533