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Unsymmetrically Substituted 9,10-Dihydro-9,10-diboraanthracenes as Versatile Building Blocks for Boron-Doped π-Conjugated Systems

Unsymmetrically Substituted 9,10-Dihydro-9,10-diboraanthracenes as Versatile Building Blocks for Boron-Doped π-Conjugated Systems

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JANUSZEWSKI, Estera, Andreas LORBACH, Rekha GREWAL, Michael BOLTE, Jan W. BATS, Hans-Wolfram LERNER, Matthias WAGNER, 2011. Unsymmetrically Substituted 9,10-Dihydro-9,10-diboraanthracenes as Versatile Building Blocks for Boron-Doped π-Conjugated Systems. In: Chemistry - A European Journal. 17(45), pp. 12696-12705. ISSN 0947-6539. eISSN 1521-3765. Available under: doi: 10.1002/chem.201101701

@article{Januszewski2011-11-04Unsym-39249, title={Unsymmetrically Substituted 9,10-Dihydro-9,10-diboraanthracenes as Versatile Building Blocks for Boron-Doped π-Conjugated Systems}, year={2011}, doi={10.1002/chem.201101701}, number={45}, volume={17}, issn={0947-6539}, journal={Chemistry - A European Journal}, pages={12696--12705}, author={Januszewski, Estera and Lorbach, Andreas and Grewal, Rekha and Bolte, Michael and Bats, Jan W. and Lerner, Hans-Wolfram and Wagner, Matthias} }

Bolte, Michael Wagner, Matthias Januszewski, Estera Bats, Jan W. Grewal, Rekha Lorbach, Andreas 2011-11-04 Lorbach, Andreas Unsymmetrically Substituted 9,10-Dihydro-9,10-diboraanthracenes as Versatile Building Blocks for Boron-Doped π-Conjugated Systems 2017-06-13T09:30:07Z Lerner, Hans-Wolfram eng Januszewski, Estera Lerner, Hans-Wolfram The targeted hydrolysis of the 9,10-dihydro-9,10-diboraanthracene adduct (Me<sub>2</sub>S)HB(C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>BH(SMe<sub>2</sub>) (1) with 0.5 equiv of H<sub>2</sub>O leads to formation of the borinic acid anhydride [(Me<sub>2</sub>S)HB(C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>B]<sub>2</sub>O (2) and thereby provides access to the field of unsymmetrically substituted 9,10-dihydro-9,10-diboraanthracenes. Compound 2 reacts with tBuC≡CH to give the corresponding vinyl derivative in an essentially quantitative conversion. Subsequent cleavage of the B-O-B bridge by LiAlH<sub>4</sub> with formation of hydridoborate functionalities is possible but is accompanied by partial B-C(vinyl) bond degradation. This situation changes when the related mesityl derivative [MesB(C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>B]<sub>2</sub>O (7) is employed, which can be synthesized from BrB(C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>BBr (6) by treatment with 1 equiv of MesMgBr and subsequent hydrolysis. The reaction of 7 with LiAlH<sub>4</sub> in tetrahydrofuran (THF) furnishes Li[MesB(C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>BH<sub>2</sub>] (8); hydride elimination with Me<sub>3</sub>SiCl leads to formation of the THF adduct MesB(C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>BH(THF) (9·THF). Alternatively, 7 can be transformed into the bromoborane MesB(C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>BBr (10) by treatment with BBr<sub>3</sub>. A Br/H-exchange reaction between 10 and Et<sub>3</sub>SiH yields the donor-free borane MesB(C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>BH (9), which forms B-H-B bridged dimers (9)<sub>2</sub> in the solid state. The vinyl borane MesB(C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>BC(H)=C(H)Mes (14) is accessible from MesC≡CH and either 9·THF or 9. Compared with the related compound Mes<sub>2</sub>BC(H)=C(H)Mes, the electronic absorption and emission spectra of 14 reveal bathochromic shifts of Δλ(abs)=17 nm and Δλ(em)=74 nm, which can be attributed to the rigid, fully delocalized π framework of the [MesB(C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>B] chromophore. Bats, Jan W. Wagner, Matthias 2017-06-13T09:30:07Z Bolte, Michael Grewal, Rekha

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