A diverse structural behaviour of boronated ortho-phthalaldehydes: A crystal structure of 1,3-dihydro-1,3-dihydroxy-4-formylbenzo[c][2,1]oxaborole

Two isomeric boronated ortho-phthalaldehydes 3- and 4-[B(OH)2]-1,2-C6H3(CHO)2 have been prepared and their specific behavior in solution under various conditions has been investigated using NMR spectroscopy. The former compound undergoes a ring-chain tautomeric rearrangement to form a cyclic structure of 1,3-dihydro-1,3-dihydroxy-4-formylbenzo[c][2,1]oxaborole predominating in acetone-d6 solution and characterized by X-ray diffraction.