Sodium borohydride → Tert-butyl 4-(5-amino-3-chloropyridin-2-yl)piperazine-1-carboxylate

Participants

Reaction Steps

Place 4-(3-chloro-5-nitro-pyridin-2-yl)-piperazine-1-carboxylic acid tert-butyl ester (3.09 g, 9.01 mmol) in methanol (50 mL). Add nickel(II) chloride hexahydrate (10.7 g, 45.1 mmol) and cool the reaction to 0° C. Add sodium borohydride (5.11 g, 135.15 mmol) in portions and stir at 0° C. for 2 hours. Add CH2Cl2 and filter through a pad of Celite®. Wash filter cake with CH2Cl2 and collect filtrate. Add saturated aq. sodium bicarbonate solution to the filtrate and separate organic layer. Extract aqueous layer with CH2Cl2 (2×30 mL). Combine organic extracts, dry over Mg2SO4, filter, and concentrate under reduced pressure. Subject residue to silica gel chromatography eluting with 0-70% EtOAc:hexane to yield 1.77 g (63%) of the title compound. MS(ES): m/z=311.2 [M−H].

Provenance & Evidence