Other methods for functionalization of remote sites

The covalent C-B bonds of organoboronic acids and esters are very inert to ionic and radical reactions, thus allowing functionalization of remote sites other than the B-G bond (Equations (94)-(97)). Bulky diols such as pinacol have been used as the protecting group of B(OH)2 because of their high stability to nucleophiles and water and silica gel in amination of 316,474 hydroboration-amination of 317,475 Wittig reaction of 3 18,476 and oxidation-alkylation of 319.477 

The G-B bond of boronic esters is inert for functionalization of remote sites other than the B-G bond by metal-catalyzed reactions (Equations (98)-(100)). Gross-coupling reactions of 320478 and 321,479 and titanium-Wittig reaction on polymer resin 323480 have been studied. 

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