Organoboronate esters, amination

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... 

Very recently, the Yuan group combined biphenol 107 and thiourea 112 to give the novel hybrid biphenol-thiourea catalyst 109 (Figure 42.5). This compound catalyzed the domino Petasis coupling of salicaldehydes 151 and cyclic secondary amines 152 employing directly aromatic or vinyl organoboronic acids 153 (instead of their esters) to give various alkylaminophenols 154 (Scheme 42.34) [82]. 

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