H-1 NMR and IR spectroscopy and mass spectrometry were used to show that th
e major products of the autooxidation of substituted 1,3,2-dioxaborinanes a
nd 1,3,2-dioxaborolanes upon prolonged handling are the corresponding 2,2'-
oxybis(1,3,2-dioxaborinanes) and a,2'-oxybis(1,3,2-dioxaborolanes). A proba
ble mechanism of this transformation is discussed.