Structure and conformational analysis of 2-hydroxy-5-isobutyl-1,3,2-dioxaborinane

The structure of 2-hydroxy-5-isobutyl-1,3,2-dioxaborinane, one of the major autooxidation products of 5-isobutyl-2-isopropyl-1,3,2-dioxaborinane, has been studied by ¹H, ¹³C, and ¹¹B NMR spectroscopy together with X-ray analysis. Molecules of the title compounds adopt a sofa conformation with equatorial isobutyl substituent. The ring interconversion path, free conformational energy, and optimal conformation of the isobutyl group (corresponding to the X-ray diffraction data) were determined by DFT quantum chemical calculations at the PBE/3ξ level of theory.