N,N,N',N'-Tetramethylethylenediamine → {4-[(tert-Butoxycarbonyl)amino]pyridin-3-yl}boronic acid

Participants

Reaction Conditions

Reaction Steps

A 2.5 M solution of n-butyl lithium in hexane (100 mL, 250 mmol) was added over 20 minutes to a stirred solution of tert-butyl pyridin-4-ylcarbamate (19.4 g, 100 mmol) and N,N,N′,N′-tetramethylethylenediamine (31.4 g, 270 mmol) in THF (500 mL) at −78° C. tert-Butyl pyridin-4-ylcarbamate is available from a literature procedure (Spivey, A. C. et al. J. Org. Chem. 1999, 64, 9430-9443). A white solid appeared and the mixture was stirred for 10 minutes at −78° C., then was allowed to warm slowly to −4° C. before cooling to −78° C. again. Trimethyl borate (39.5 g, 380 mmol) was added over 15 minutes. The solution was allowed to warm to 0° C., then was poured into saturated aqueous ammonium chloride (500 mL). The mixture was stirred for 2 minutes. After standing at ambient temperature overnight, the mixture was partitioned between diethyl ether and brine. The organic layer was separated and washed with brine. A white solid formed in the organic layer and was isolated by filtration. The solid was washed sequentially with diethyl ether, water, and diethyl ether, then was dried to provide 17.1 g of 4-[(tert-butoxycarbonyl)amino]pyridin-3-ylboronic acid as a white solid.

Provenance & Evidence