2,4,6-TRI-T-BUTYLPHENYL-SUBSTITUTED IMINOBORANE

Iminoboranes RBNR′: IIb (R′ t-Bu) and IIc (R′ SiMe3) carrying the super-mesityl group (R) on the boron atoms have been prepared by thermal elimination of fluorotrimethylsilane from the relevant fluoro(trimethylsilylamino)borane precursors Ib and Ic. The intermediate IIa (R′ i-Pr) rearranges to give the benzo[1]borolane derivative IIIa. However IIa (and also IIb) are obtained by HF-elimination with t-BuLi from the corresponding fluoro(amino)boranes IVa and IVb at low temperature, the iminoboranes IIa-IIc are thermally stable at temperatures of more than 200°C and the benzo[1]borolanes IIIb and IIIc are formed at 350 and 250°C, resp. H acidic compounds HX (X OH, O-t-Bu, HN-t-Bu, Cl) are readily added to IIc to give aminoboranes Va-Vd. The iminoborane VII: t-Bu-BNR was prepared from F2BNHR (VI) and two moles t-BuLi. The compounds are characterized by elemental analyses and spectroscopic data (MS, IR, NMR: 1H, 11B, 13C, 15N, 19F, 29Si). X-ray diffraction studies have been performed on IIb and Va. © 1990.