Diborylated Magnesium Anthracene as Precursor for B2H5−‐Bridged 9,10‐Dihydroanthracene |
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| Authors: | Steffen Pospiech Dr Michael Bolte Dr Hans‐Wolfram Lerner Prof?Dr Matthias Wagner |
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| Affiliation: | J.?W. Goethe‐Universit?t, Institut für Anorganische und Analytische Chemie, Max‐von‐Laue‐Stra?e 7, 60438 Frankfurt (Main) (Germany), Fax: (+49)?69‐798‐29260 |
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| Abstract: | 9,10‐(Bpin)2‐anthracene ( 3 , HBpin=pinacolborane) was synthesized from 9,10‐dibromoanthracene in a stepwise lithiation/borylation sequence. The reaction of 3 with highly activated magnesium furnished the diborylated magnesium anthracene 4 , which was quenched in situ with ethereal HCl to yield cis‐9,10‐(Bpin)2‐DHA (cis‐ 5 , DHA=9,10‐dihydroanthracene). Compound cis‐ 5 , in turn, can be reduced with LiAlH4] in THF to give its diborate Li2cis‐9,10‐(BH3)2‐DHA] (Li2cis‐ 6 ]). In the crystal lattice, the THF solvate Li2cis‐ 6 ] ? 3 THF establishes a dimeric structure with Li‐(μ‐H)‐B coordination modes. Hydride abstraction from Li2cis‐ 6 ] with Me3SiCl yields the B?H?B‐bridged DHA Li 7 ]. This product can also be viewed as a unique cyclic B2H7? derivative with a hydrocarbon backbone. Treatment of Li2cis‐ 6 ] with the stronger hydride abstracting agent Me3SiOTf (HOTf=trifluoromethanesulfonic acid) in THF affords the THF diadduct of cis‐9,10‐(BH(OTf))2‐DHA. |
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| Keywords: | boranes hydride abstraction hydrido complexes magnesium anthracenes reduction |
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