Improved Synthesis of 1,2‐Bis(trimethylsilyl)benzenes using Rieke‐Magnesium or the Entrainment Method

Lorbach, Andreas; Reus, Christian; Bolte, Michael; Lerner, Hans‐Wolfram

doi:10.1002/adsc.201000560

Cited by 35 publications

(48 citation statements)

References 47 publications

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“…Synthesis and characterization of 1,2‐C 6 H 4 (Bpin) 2 (2) : In analogy to our recently reported synthesis of 1,2‐bis(trimethylsilyl)benzene,53 compound 2 was prepared from 1,2‐dibromobenzene ( 1 ), isopropoxypinacolborane, and Mg turnings in the presence of 1,2‐dibromoethane as an entrainer (Scheme ). This entrainment method51 ensured a continuous activation of the Mg surface by a dropwise addition of the entrainer compound into the reaction mixture.…”

Section: Resultsmentioning

confidence: 99%

“…Herein, we report a time‐ and cost‐efficient uncatalyzed Grignard route to 1,2‐bis(pinacolboryl)benzene (1,2‐C 6 H 4 (Bpin) 2 , 2 ; Scheme ). This route uses the “entrainment method”51–53 and provides a convenient access to multigram quantities of the product. With the aim of developing new building blocks for boron‐containing optoelectronic materials,24, 25 we have subsequently used compound 2 to synthesize the ditopic trihydroborate Li 2 [1,2‐C 6 H 4 (BH 3 ) 2 ] ( 3 ; Scheme ) and we have investigated the chemical properties of the corresponding ditopic borane 1,2‐C 6 H 4 (BH 2 ) 2 by experimental and quantum‐chemical means.…”

Section: Introductionmentioning

confidence: 99%

“…[50] Herein, we report a time-and cost-efficient uncatalyzed Grignard route to 1,2-bis(pinacolboryl)benzene (1,2-C 6 H 4 -A C H T U N G T R E N N U N G (Bpin) 2 , 2; Scheme 1). This route uses the "entrainment method" [51][52][53] and provides a convenient access to multigram quantities of the product. With the aim of developing new building blocks for boron-containing optoelectronic materials, [24,25] we have subsequently used compound 2 to synthesize the ditopic trihydroborate…”

Section: Introductionmentioning

confidence: 99%

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Synthesis, Coupling, and Condensation Reactions of 1,2‐Diborylated Benzenes: An Experimental and Quantum‐Chemical Study

Seven

Zhu

et al. 2012

Chemistry A European J

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1,2-Bis(pinacolboryl)benzene (1,2-C(6)H(4) (Bpin)(2), 2) was synthesized in preparatively useful yields from 1,2-C(6)H(4)Br(2), iPrO-Bpin, and Mg turnings in the presence of 1,2-C(2)H(4)Br(2) as an entrainer. Compound 2 is a versatile starting material for the synthesis of (un)symmetrically substituted benzenes (i.e., 1,2-C(6)H(4)(Ar(1))(Ar(2))) through sequential Suzuki-Miyaura coupling reactions. Alternatively, it can be transformed into bis-borate Li(2)[1,2-C(6)H(4)(BH(3))(2)] (3) through reduction with Li[AlH(4)]. In the crystal lattice, the diethyl ether solvate 3·OEt(2) establishes a columnar structure that is reinforced by an intricate network of B-(μ-H)-Li interactions. Hydride-abstraction from compound 3 with Me(3)SiCl leads to the transient ditopic borane 1,2-C(6)H(4)(BH(2))(2), which can either be used in situ for subsequent hydroboration reactions or trapped as its stable NMe(2)Et diadduct (6). In SMe(2) solution, the putative diadduct 1,2-C(6)H(4)(BH(2)·SMe(2))(2) is not long-term stable but rather undergoes a condensation reaction to give 9,10-dihydro-9,10-diboraanthracene, HB(μ-C(6)H(4))(2)BH, and BH(3). 9,10-Dihydro-9,10-diboraanthracene was isolated from the reaction mixture as its SMe(2) monoadduct (7), which dimerizes in the solid state through two B-H-B bridges ((7)(2), elucidated by X-ray crystallography). In contrast, hydride-abstraction from compound 3 in THF or CH(2)Cl(2) provides the unique exo-adduct H(2)B(μ-H)(2)B(μ-C(6)H(4))(2)B(μ-H)(2)BH(2) (8, elucidated by X-ray crystallography). Quantum-chemical calculations on various conceivable isomers of [1,2-C(6)H(4)(BH(2))(2)](2) revealed that compound 8 was the most stable of these species. Moreover, the calculations confirmed the experimental findings that the NMe(2)Et diadduct of 1,2-C(6)H(4)(BH(2))(2) is significantly more stable than the corresponding SMe(2) complex and that the latter complex is not able to compete successfully with borane-dimerization and -condensation. The reaction cascade in SMe(2), which proceeds from 1,2-C(6)H(4)(BH(2))(2) to the observed adducts of HB(μ-C(6)H(4))(2)BH, has been elucidated in detail and the important role of B-C-B-bridged intermediates has been firmly established.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis, Coupling, and Condensation Reactions of 1,2‐Diborylated Benzenes: An Experimental and Quantum‐Chemical Study

Seven

Zhu

et al. 2012

Chemistry A European J

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“…As a downside of these approaches, functionalization is now largely restricted to variations of the phenylene substituents R′. A new bottom‐up synthesis of halogenated DBAs (R′=F, Cl, Br) was therefore required and subsequent coupling protocols had to be developed to introduce, for example, 2‐thienyl moieties as R′ groups …”

Section: Introductionmentioning

confidence: 99%

How Boron Doping Shapes the Optoelectronic Properties of Canonical and Phenylene‐Containing Oligoacenes: A Combined Experimental and Theoretical Investigation

Kirschner

Mewes

Bolte

et al. 2017

Chemistry A European J

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Optimized syntheses of 6,13-dimesityl-6,13-dihydro-6,13-diborapentacene (DBP) and a related compound (DBI) featuring two biphenylene-2,3-diyl units in place of naphthalene-2,3-diyl moieties are reported. Striking differences between the optoelectronic properties of DBP and DBI have been experimentally observed, and explained by quantum chemical calculations. DBP is a member of the oligoacene family, DBI is a linear [N]phenylene derivative. The yellow DBP shows blue photoluminescence, the deep red DBI is nonfluorescent. Both compounds give rise to two reversible redox transitions at E1/2 =-2.03 V, -2.75 V (DBP) and -1.52 V, -2.30 V (DBI; THF, vs. FcH/FcH ). The higher electron affinity of DBI agrees with a lower calculated LUMO energy level [-0.57 eV for DBI with respect to DBP @HF//SCS-MP2/def2-TZVP] and a higher Lewis acidity of its boron centers, which is reflected in the trend of adduct formation with small Lewis bases (MeCN, F ). The thermochemistry underlying this trend, as well as the mechanism of fluorescence quenching in DBI, are revealed by state-of-the-art quantum chemical calculations. It is suggested that the nonradiative deactivation occurs via a low-lying, doubly excited state.

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“…The fully trimethylsilylated bisallene 88 is produced when hexabromide 87 is treated with excess trimethylsilyl chloride and Rieke magnesium at 0 °C (Scheme 20) [69–70]. The yield is low, however, and several other isomers of 88 are present in the reaction mixture.…”

Section: Reviewmentioning

confidence: 99%

The chemistry of bisallenes

Hopf¹,

Μαρκόπουλος²

2012

Beilstein J. Org. Chem.

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SummaryThis review describes the preparation, structural properties and the use of bisallenes in organic synthesis for the first time. All classes of compounds containing at least two allene moieties are considered, starting from simple conjugated bisallenes and ending with allenes in which the two cumulenic units are connected by complex polycyclic ring systems, heteroatoms and/or heteroatom-containing tethers. Preparatively the bisallenes are especially useful in isomerization and cycloaddition reactions of all kinds leading to the respective target molecules with high atom economy and often in high yield. Bisallenes are hence substrates for generating molecular complexity in a small number of steps (high step economy).

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Improved Synthesis of 1,2‐Bis(trimethylsilyl)benzenes using Rieke‐Magnesium or the Entrainment Method

Cited by 35 publications

References 47 publications

Synthesis, Coupling, and Condensation Reactions of 1,2‐Diborylated Benzenes: An Experimental and Quantum‐Chemical Study

Synthesis, Coupling, and Condensation Reactions of 1,2‐Diborylated Benzenes: An Experimental and Quantum‐Chemical Study

How Boron Doping Shapes the Optoelectronic Properties of Canonical and Phenylene‐Containing Oligoacenes: A Combined Experimental and Theoretical Investigation

The chemistry of bisallenes

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