1361054-72-9Relevant academic research and scientific papers
Unsymmetrically substituted 9,10-dihydro-9,10-diboraanthracenes as versatile building blocks for boron-doped π-conjugated systems
Januszewski, Estera,Lorbach, Andreas,Grewal, Rekha,Bolte, Michael,Bats, Jan W.,Lerner, Hans-Wolfram,Wagner, Matthias
, p. 12696 - 12705 (2011/12/22)
The targeted hydrolysis of the 9,10-dihydro-9,10-diboraanthracene adduct (Me2S)HB(C6H4)2BH(SMe2) (1) with 0.5 equiv of H2O leads to formation of the borinic acid anhydride [(Me2S)HB(C6H4)2B] 2O (2) and thereby provides access to the field of unsymmetrically substituted 9,10-dihydro-9,10-diboraanthracenes. Compound 2 reacts with tBuCi￡CH to give the corresponding vinyl derivative in an essentially quantitative conversion. Subsequent cleavage of the B-O-B bridge by LiAlH 4 with formation of hydridoborate functionalities is possible but is accompanied by partial BiC(vinyl) bond degradation. This situation changes when the related mesityl derivative [MesB(C6H4) 2B]2O (7) is employed, which can be synthesized from BrB(C6H4)2BBr (6) by treatment with 1 equiv of MesMgBr and subsequent hydrolysis. The reaction of 7 with LiAlH4 in tetrahydrofuran (THF) furnishes Li[MesB(C6H4) 2BH2] (8); hydride elimination with Me3SiCl leads to formation of the THF adduct MesB(C6H4) 2BH(THF) (9 THF). Alternatively, 7 can be transformed into the bromoborane MesB(C6H4)2BBr (10) by treatment with BBr3. A Br/H-exchange reaction between 10 and Et3SiH yields the donor-free borane MesB(C6H4)2BH (9), which forms B-H-B bridged dimers (9)2 in the solid state. The vinyl borane MesB(C6H4)2BC(H)-C(H)Mes (14) is accessible from MesCi￡CH and either 9 THF or 9. Compared with the related compound Mes2BC(H)-C(H)Mes, the electronic absorption and emission spectra of 14 reveal bathochromic shifts of I-(abs)=17 nm and I-(em)=74 nm, which can be attributed to the rigid, fully delocalized π framework of the [MesB(C6H4)2B] chromophore. Putting boron in the ring: The unsymmetrically substituted 9,10-dihydro-9,10-diboraanthracene MesB(C6H4)2BH, which exists as a dimeric species in the solid state and shows strong photoluminescence (see figure), is a versatile reagent that can be used to introduce a rigid, boron-doped moiety into conjugated π-electron systems through hydroboration reactions.
