tert-Butyl 3-((3-(4,4,5,5-tetramethyl-1,3,2-dioxab orolan-2-yl)pyridin-2-yloxy)methyl)pyrrolidine-1-ctert-Butyl 3-((3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridin-2-yloxy)methyl)pyrrolidine-1-carboxylatetert-Butyl 3-((3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridin-2-yloxy)methyl)pyrrolidine-1-carboxylate