(Diethylamino)sulfur trifluoride → tert-butyl 8-bromo-4-fluoro-3,4-dihydroisoquinoline-2(1H)-carboxylate

Participants

Reaction Steps

To a flask containing tert-butyl 8-bromo-4-hydroxy-3,4-dihydroisoquinoline-2(1H)-carboxylate (24-4) (622 mg, 1.895 mmol) was added anhydrous DCM (10 ml). The reaction mixture was then capped & cooled to −78 C (dry ice/acetone bath) while stirring under N2. Then added DAST (1.4 ml, 10.60 mmol) at −78 C. The reaction mixture was then stirred at −78 C. Followed by LC/MS. After 5 minutes at −78 C the reaction was quenched by dropwise addition of a saturated solution of NaHCO3 in water at −78 C (with a vent needle), then permitted to warm to room temperature, then the reaction mixture was suspended in EtOAc, washed with saturated NaHCO3, then H2O, then brine; organics dried over Na2SO4, filtered & concentrated to yield. Purification by silica gel chromatography (0-15% EtOAc/Hex; 40 g ISCO); desired fractions concentrated to yield tert-butyl 8-bromo-4-fluoro-3,4-dihydroisoquinoline-2(1H)-carboxylate (24-5).

Provenance & Evidence