Imidazole → [(3R)-5-Bromo-1,2,3,4-tetrahydroisoquinolin-3-YL]methoxy-tert-butyl-dimethyl-silane

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Reaction Steps

Add trifluoroacetic acid (75.5 mL, 998.3 mmol) to solution of tert-butyl (3R)-5-bromo-3-(hydroxymethyl)-3,4-dihydro-1H-isoquinoline-2-carboxylate (15.5 g, 45.3 mmol) in dichloromethane (226 mL) at room temperature. Stir 30 min and concentrate under reduced pressure. Dry under vacuum to give [(3R)-5-bromo-1,2,3,4-tetrahydroisoquinolin-3-yl]methanol; 2,2,2-trifluoroacetic acid as a wet solid. Dissolve [(3R)-5-bromo-1,2,3,4-tetrahydroisoquinolin-3-yl]methanol; 2,2,2-trifluoroacetic acid in dichloromethane (753 mL). Add 1H-imidazole (51.3 g, 753 mmol), N,N-Dimethyl-4-pyridinamine (460 mg, 3.77 mmol), and t-butyldimethylchlorosilane (13.6 g, 90.4 mmol). Stir at room temperature overnight. Add saturated ammonium chloride solution and extract with dichloromethane. Dry the dichloromethane extracts over sodium sulfate, filter, and concentrate under reduced pressure. Combine with the crude product from a substantially same reaction run with 19.4 mmol of tert-butyl (3R)-5-bromo-3-(hydroxymethyl)-3,4-dihydro-1H-isoquinoline-2-carboxylate. Purify the residue by silica gel chromatography eluting with ethyl acetate: hexanes (5-40% gradient) to give the title compound (14.3 g, 40.1 mmol). MS (m/z): 356 (M+1).

Provenance & Evidence