Boron tribromide → alpha-[2-(Diisopropylamino)ethyl]-alpha-(4-hydroxyphenyl)-2-pyridineacetamide

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Reaction Steps

A solution of 7.32 grams (g) [0.02 moles (mol)] of α-[2-(diisopropylamino)ethyl]-α-(4-methoxyphenyl)-2-pyridineacetamide [Karim, supra] in 250 milliliters (mL) of methylene chloride (CH2Cl2) was cooled to -78° C. while stirring under an inert atmosphere. To this was added dropwise 19.85 g (0.08 mol) of boron tribromide dissolved in 50 mL of CH2Cl2. The resulting brown suspension was allowed to warm to room temperature, then was heated at reflux for 1 hour. It was cooled to -10° C., and excess boron tribromide destroyed by the addition of 150 mL of 10% sodium hydroxide (NaOH) solution. The organic phase was separated and extracted with n-butanol. Evaporation left a residue which was purified by chromatography on silica gel eluting with 60:10:1 (v/v/v) CHCl3 :MeOH:conc. ammonium hydroxide. This gave 4.8 g of the phenol as a pale tan solid. A sample was recrystallized from toluene to give a solid, mp 148°-151° C.

Provenance & Evidence