Trifluoroacetic acid → 8-(((Tert-butyldiphenylsilyl)oxy)methyl)-1-isopropyl-7-(methylsulfonyl)-3,4-dihydropyrazino[1,2-a]indole

Participants

Reaction Steps

To a solution of tert-butyl(2-(5-(((tert-butyldiphenylsilyl)oxy)methyl)-2-isobutyryl-6-(methylsulfonyl)-1H-indol-1-yl)ethyl)carbamate (250 mg, 0.37 mmol) in CH2Cl2 (5.0 mL) was added trifluoroacetic acid (1.0 mL) and the mixture was allowed to stir at rt for 1 h. The excess amount of TFA was removed by azeotropic evaporation with toluene under reduced pressure. The residue was redissolved in CH2Cl2 (5 mL) and Et3N (0.5 mL) was added. The reaction mixture was stirred at rt for 45 min and concentrated in vacuo. The residue was purified by flash chromatography over silica gel eluting with CH2Cl2/methanol (98/2) to provide 8-(((tert-butyldiphenylsilyl)oxy)methyl)-1-isopropyl-7-(methylsulfonyl)-3,4-dihydropyrazino[1,2-a]indole (135 mg, 65% yield). LC-MS m/z 559 [M+H]+.

Provenance & Evidence