Tert-butyl 2-(2-(4-chlorophenoxy)ethyl)-2-(diphenylmethyleneamino)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoate → 2-Amino-6-borono-2-(2-(4-chlorophenoxy)ethyl)hexanoic acid hydrochloride

Participants

Reaction Steps

A solution of 2-(benzhydrylidene-amino)-2-[2-(4-chlorophenoxy)-ethyl]-6-(4,4,5,5-tetramethyl-[1,3,2]-dioxaborolan-2-yl)-hexanoic acid tert-butyl ester (486 mg) in 6 N HCl (6 ml) was warmed to 60° C. and stirred overnight. After cooling to room temperature, the reaction mixture was transferred to a separatory funnel, diluted with deionized water (6 ml) and washed with dichloromethane (3×). The aqueous layer was frozen in liquid nitrogen and lyophilized to give 2-amino-6-borono-2-(2-(4-chlorophenoxy)ethyl)hexanoic acid hydrochloride, as a colorless foam (125 mg, 85%); 1H NMR (D4-MeOH, 300 MHz) δH 7.24 (2H, d, J=7 Hz, 2H), 6.94 (d, J=7 Hz, 2H), 4.18 (m, 2H), 2.52 (m, 1H), 2.46 (m, 1H), 1.92 (m, 2H), 1.22-1.52 (m, 4H) and 0.82 (t, J=7 Hz, 2H,); MS (+CI): m/z for C14H21BClNO5: expected 329.1. found 330.2 (M+H)+, 312.2 (M+H−H2O)+, 659.4 (2 M+H)+, 641.4 (2 M+H−H2O)+.

Provenance & Evidence