Four-coordinate organoboron compounds from β-enaminonitriles and diazonium salts

β-Enaminonitriles react with substituted benzenediazonium tetraphenylborates to form 1,2,4,3λ4-triazaborines or 1,3,2λ4-oxazaborines. The formation of either the first or the second product is affected by the reaction conditions, especially by the presence of water in the reaction components and in the solvent. If the reaction is performed under anhydrous conditions, the major product is the triazaborine. When ‘wet’ diazonium salts are used or a small amount of water is added into the reaction mixture, oxazaborine is the product.