Boron trifluoride etherate → 1-(2-(Benzyloxy)-3-fluorophenyl)cyclopropanamine

Participants

Reaction Conditions

Reaction Steps

A solution of ethylmagnesium bromide, 3M in diethyl ether (28.2 mL) was added as a slow stream to a mechanically stirred mixture of tetraisopropyl orthotitanate (13.09 mL), and 2-(benzyloxy)-3-fluorobenzonitrile (Example 283a, 9.6 g) in diethyl ether (400 mL) cooled to −78° C. The resulting solution was stirred at −78° C. for 15 min and then warmed to room temperature over 1 h 30 min. An ice bath was placed around the reaction and boron trifluoride etherate (10.71 mL) was added as a slow stream (caution exothermic) and the mixture was stirred for 30 min. The reaction was cooled (ice bath) and quenched with 1 M aqueous HCl (400 mL added portionwise). The aqueous layer was separated and the diethyl ether layer further extracted into 1M HCl (2×200 mL) (ethyl acetate added to the diethyl ether to aid solubility). The aqueous layer was cooled in an ice bath and basified with stirring with a 10M aqueous NaOH solution. The resulting precipitate was filtered through Celite, washing the pad with water (200 mL) then DCM (4×200 mL) then DCM/MeOH (90:10, 300 mL). The combined filtrates were separated and the aqueous layer further extracted with DCM (2×200 mL). The combined organics were dried (MgSO4) and evaporated, the residue was purified on SCX resin (50 g) eluting with DCM, methanol (discarded) and flushing with 20% ammonia in methanol to give the subtitle compound as an oil (2.54 g).

Provenance & Evidence