2-(4-tert-Butoxycarbonylpiperazin-1-yl)pyridine-4-boronic acid, pinacol ester2-[4-(tert-Butoxycarbonyl)piperazin-1-yl]-4-(4,4,5,5-tetramethyl,1,3,2-dioxaborolan-2-yl)pyridine2-[4-(tert-Butoxycarbonyl)piperazin-1-yl]pyridine-4-boronic acid, pinacol ester