Diisopropylethylamine → (R)-methyl 1-(4-fluorophenyl)-6-((3-(trifluoromethyl)phenyl)sulfonyl)-4,4a,5,6,7,8-hexahydro-1H-pyrazolo[3,4-g]isoquinoline-4a-carboxylate

Participants

Reaction Steps

A solution of (R)-6-tert-butyl 4a-methyl 1-(4-fluorophenyl)-4a,5,7,8-tetrahydro-1H-pyrazolo[3,4-g]isoquinoline-4a,6(4H)-dicarboxylate (2.0 g, 4.68 mmol) in 20% trifluoroacetic acid/dichloromethane (50 mL) was stirred at room temperature for 1 hour. The solvent was removed in vacuo, azeotroping three times with toluene (˜20 mL), to give a dark orange oil. The oil was dissolved in dichloromethane (50 mL) and 3-(trifluoromethyl)benzene-1-sulfonyl chloride (0.900 ml, 5.61 mmol) was added followed by diisopropylethylamine (4.09 ml, 23.39 mmol). The reaction mixture was stirred at room temperature for 20 minutes, and then solvent removed in vacuo to give a dark orange oil. The crude product was purified by chromatography on silica gel (gradient: 0-45% ethyl acetate in isohexane) to afford (R)-methyl 1-(4-fluorophenyl)-6-((3-(trifluoromethyl)phenyl)sulfonyl)-4,4a,5,6,7,8-hexahydro-1H-pyrazolo[3,4-g]isoquinoline-4a-carboxylate (931 mg) as a pale yellow solid. LCMS (Method F, ES-API): RT 2.62 min, m+H=536.2.

Provenance & Evidence