Synthesis and Reactivity of a Naphtho[l,8‐<i>bc</i>]boret

Hergel, Achim; Pritzkow, Hans; Siebert, Walter

doi:10.1002/anie.199412471

Cited by 45 publications

(27 citation statements)

References 11 publications

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“…3 In addition, our group showed that the one-electron reduction of 1,8-bis(diphenylboryl)naphthalene can lead to the generation of σ-delocalized radicals. 10 As part of our general interest in this chemistry, we have recently described a rare example of a boron peri-bridged naphthalene derivative, 11 namely dimesityl-1,8-naphthalenediylborate (1). 12 This strained cyclic borate undergoes ring opening reactions in the presence of various electrophiles 13 and its reaction with diorganylboronhalides afford unsymmetrically substituted 1,8-diborylnaphthalenes.…”

Section: Introductionmentioning

confidence: 99%

Reactivity of the dimesityl-1,8-naphthalenediylborate anion: isolation of the borataalkene isomer and synthesis of 1,8-diborylnaphthalenes

2004

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The anionic boron peri-bridged naphthalene derivative, namely dimesityl-1,8-naphthalenediylborate (1), undergoes a hydrolysis reaction to afford dimesityl-1-naphthylborane (2) whose structure has been determined. Upon standing at room temperature in toluene for an extended period of time, 1 undergoes a ring expansion reaction to afford 8,10,11a-trimethyl-7-mesityl-11aH-7-boratabenzo[de]anthracene (3). As shown by its crystal structure, compound 3 constitutes a rare example of a borataalkene and features a carbon-boron double bond of 1.475(6) Angstroms incorporated in a conjugated hexa-1-boratatriene system. The reaction of 1 with 9-chloro-9-borafluorene and 5-bromo-10,11-dihydrodibenzo[b,f]borepin results in the formation of diboranes 4 and 5 which bear two different boryl moieties at the peri-positions of naphthalene. These diboranes have been characterized by multinuclear NMR spectroscopy and X-ray single crystal analysis. The boron center of the borafluorenyl moiety is pi-coordinated to the ipso-carbon of a mesityl group with which it forms a contact of 2.730(3) Angstroms. The cyclic voltammogram of 2 in THF shows a quasi-reversible reduction wave at E(1/2)-2.41 V (vs. Fc/Fc+) corresponding to the formation of the radical anion. In the case of diboranes 4, 5 and 1-(dimesitylboryl)-8-(diphenylboryl)naphthalene (6), two distinct waves are observed at E(1/2)-2.14 and -2.56 V for 4, E(1/2)-2.26 and -2.78 V for 5, and E(1/2)-2.41 and -2.84 V for 6. The first reduction wave most likely indicates the formation of a radical anion in which the unpaired electron is sigma-delocalized over the two boron centers.

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Section: Introductionmentioning

confidence: 99%

Reactivity of the dimesityl-1,8-naphthalenediylborate anion: isolation of the borataalkene isomer and synthesis of 1,8-diborylnaphthalenes

2004

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“…In the case of four-membered boron containing rings, the 1,8-disubsitituted naphthalene platform has been employed in the synthesis of the four-membered borete 1 or boretate 2. [3] The peri-substitution pattern in the naphthalene scaffold essentially stabilises the four-membered ring architecture with a bridged single boron centre. Interestingly, besides 1 and 2 only a few other examples of boretanes or boretes have been reported, [4] and a comprehensive understanding of their reactivity is currently missing.…”

Section: Introductionmentioning

confidence: 99%

Reactions of a Four‐Membered Borete with Carbon, Silicon, and Gallium Donor Ligands: Fused and Spiro‐Type Boracycles

Güven

Denker

Dolati

et al. 2022

Chemistry A European J

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Donor‐acceptor cyclopropanes or cyclobutanes are dipolar reagents, which are widely used in the synthesis of complex organic (hetero)cycles in ring expansion reactions. Applying this concept to boron containing heterocycles, the four‐membered borete cyclo‐iPr2N‐BC10H6 reacted with the carbon donor ligands 2,6‐xylylisonitrile and the carbene IMes :C(NMesCH)2 with ring expansion and ring fusion, respectively. In particular, the tetracyclic structure formed with IMes displays zwitterionic character and absorption in the visible region. In contrast to the carbene IMes, the heavier carbenoids :Si(NDippCH)2 and :Ga(AmIm) with a two‐coordinate donor atom afford spiro‐type bicyclic compounds, which display four‐coordinate geometry at silicon or gallium. (TD‐)DFT calculations provide deeper insight into the mechanism of formation and the absorption properties of these new compounds.

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“…We emphasize that the only alternative access route to E-type compounds proceeds via the ring-opening reaction of a highly strained naphtho[1,8-bc]boret with BX 3 and has so far been reported only for substituents R = Cl, Br, OEt and R′ = i-Pr. 25 ■ RESULTS AND DISCUSSION Synthesis of Compounds 2−8. The key starting material for the syntheses of our BEB-doped phenalenyl derivatives (E = NR′, O) was the 1,8-naphthalenediyl-bridged diborane( 6) 2 (Scheme 1).…”

Section: ■ Introductionmentioning

confidence: 99%

“…The optoelectronic properties of selected derivatives of E are reported, as well as their reactivity under reducing conditions. We emphasize that the only alternative access route to E -type compounds proceeds via the ring-opening reaction of a highly strained naphtho[1,8- bc ]boret with BX 3 and has so far been reported only for substituents R = Cl, Br, OEt and R′ = i -Pr …”

Section: Introductionmentioning

confidence: 99%

BNB-Doped Phenalenyls: Modular Synthesis, Optoelectronic Properties, and One-Electron Reduction

et al. 2020

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A highly modular synthesis of BNB- and BOB-doped phenalenyls is presented. Treatment of the 1,8-naphthalenediyl-bridged boronic acid anhydride 1 with LiAlH4/Me3SiCl afforded the corresponding 1,8-naphthalenediyl-supported diborane(6) 2, which served as the starting material for all subsequent transformations. Upon addition of MesMgBr/Me3SiCl, 2 was readily converted to the tetraorganyl diborane(6) 5. The further heteroatoms were finally introduced through the reaction of 2 with (Me3Si)2NR′ or 5 with H2NR′ or H2O (R′ = H, Me, p-Tol). A helically twisted, fully BNB-embedded PAH 11 was prepared by combining 2 with a dibrominated m-terphenylamine, followed by a Grignard-mediated double ring-closure reaction. All compounds devoid of B–H bonds show favorable optoelectronic properties, such as luminescence and reversible reduction behavior. In the case of the BNB-phenalenyl 7 (BMes, NMe), the radical-anion salt K[7 •] was generated through chemical reduction with K metal and characterized by EPR spectroscopy. K[7 •] is not long-term stable in a THF/c-hexane solution, but abstracts an H atom with formation of the diamagnetic BNB-doped 1H-phenalene K[7H].

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Synthesis and Reactivity of a Naphtho[l,8‐bc]boret

Cited by 45 publications

References 11 publications

Reactivity of the dimesityl-1,8-naphthalenediylborate anion: isolation of the borataalkene isomer and synthesis of 1,8-diborylnaphthalenes

Reactivity of the dimesityl-1,8-naphthalenediylborate anion: isolation of the borataalkene isomer and synthesis of 1,8-diborylnaphthalenes

Reactions of a Four‐Membered Borete with Carbon, Silicon, and Gallium Donor Ligands: Fused and Spiro‐Type Boracycles

BNB-Doped Phenalenyls: Modular Synthesis, Optoelectronic Properties, and One-Electron Reduction

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