4-Bromoisoquinoline → 1-Tert-butoxycarbon-yl-4-(isoquinolin-4-yl)-4-hydroxypiperidine

Participants

Reaction Steps

A solution of 6.46 gm (31.1 mMol) 4-bromoisoquinoline in 80 mL tetrahydrofuran was cooled to −100° C. under a nitrogen atmosphere. To this solution was added dropwise 28.7 mL (37.3 mmol) sec-butyllithium (1.3 M in hexanes) and the reaction mixture was allowed to stir for 1.5 hours. To the reaction mixture was then added dropwise a solution of 1-tert-butoxycarbonyl-4-piperidone in 20 mL tetrahydrofuran dropwise. The reaction mixture was then stirred for 18 hours at room temperature. The reaction mixture was then partitioned between ethyl acetate and 2N sodium hydroxide. The phases were separated and the aqueous phase extracted well with ethyl acetate. The organic phases were combined, washed saturated aqueous sodium chloride, dried over sodium sulfate and concentrated under reduced pressure. The residue was subjected to silica gel chromatography, eluting with 9:1 dichloromethane:methanol. Fractions containing product were combined and concentrated under reduced pressure to provide 3.95 gm (39%) 1-tert-butoxycarbonyl-4-(isoquin-olin-4-yl)-4-hydroxypiperidine as a yellow solid.

Provenance & Evidence