Sulfuric Acid → (S)-methyl 2-(2-amino-7-(4-chlorophenyl)-5-methylbenzo[d]thiazol-6-yl)-2-tert-butoxyacetate

Participants

Reaction Steps

To a solution of Preparation of (S)-2-(2-amino-7-(4-chlorophenyl)-5-methylbenzo[d]thiazol-6-yl)-2-tert-butoxyacetic acid from above in MeOH (25 mL) was added H2SO4 (200 μL). The reaction mixture was stirred at overnight. EtOAc (20 mL) and saturated NaHCO3 solution (50 mL) were added. The layers were separated, dried, filtered, and concentrated in vacuo. The crude mixture was a mixture of the desired (S)-methyl 2-(2-amino-7-(4-chlorophenyl)-5-methylbenzo[d]thiazol-6-yl)-2-tert-butoxyacetate and (S)-methyl 2-(2-amino-7-(4-chlorophenyl)-5-methylbenzo[d]thiazol-6-yl)-2-hydroxyacetate. t-Butyl acetate was added (20 mL) and perchloric acid (500 μL). The mixture was stirred at rt for 3 hr, where all (S)-methyl 2-(2-amino-7-(4-chlorophenyl)-5-methylbenzo[d]thiazol-6-yl)-2-hydroxyacetate was converted to (S)-methyl 2-(2-amino-7-(4-chlorophenyl)-5-methylbenzo[d]thiazol-6-yl)-2-tert-butoxyacetate. EtOAc (10 mL) and saturated NaHCO3 solution (50 mL) were added. The layers were separated, dried, filtered, and concentrated in vacuo. LCMS-ESI+: calc'd for C21H23ClN2O3S: 419.1 and 421.1 (M+H+); found: 419.2 and 421.2 (M+H+).

Provenance & Evidence