Carbon Insertion into arachno-6,9-C2B8H14 via Acyl Chlorides. Skeletal Alkylcarbonation (SAC) Reactions: A New Route for Tricarbollides

详细信息    查看全文

• 作者：Mario Bakardjiev ; Bohumil 艩t铆br ; Josef Holub ; Zde艌ka Pad臎lkov谩 ; Ale拧 R暖啪i膷ka
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：August 5, 2013
• 年：2013
• 卷：52
• 期：15
• 页码：9087-9093
• 全文大小：394K
• 年卷期：v.52,no.15(August 5, 2013)
• ISSN：1520-510X

文摘

Reactions between arachno-6,9-C₂B₈H₁₄ (1) and selected acyl chlorides, RCOCl, in the presence of PS (PS = 鈥減roton sponge鈥? 1,8-dimethylamino naphthalene) in CH₂Cl₂ for 24 h at reflux, followed by in situ acidification with concentrated H₂SO₄ at 0 掳C, generate a series of neutral alkyl and aryl tricarbollides 8-R-nido-7,8,9-C₃B₈H₁₁ (2) (where R = CH₃, 2a; C₂H₅, 2b; n-C₄H₉, 2c; C₆H₅, 2d; 4-Cl-C₆H₄, 2e; 4-Br-C₆H₄, 2f; 4-I-C₆H₄, 2g; 1-C₁₀H₇, 2h; and 2-C₁₀H₇, 2i). The best yields were achieved for aryl derivatives (80鈥?5%) while the yields of the corresponding alkyl substituted compounds are lower (60鈥?0%). These skeletal alkylcarbonation (SAC) reactions are consistent with an aldol-type condensation between the RCO group and open-face hydrogen atoms on the dicarbaborane 1, which is associated with the insertion of the carbonyl carbon atom into the structure of arachno-6,9-C₂B₈H₁₄ (1) under elimination of three extra hydrogen atoms as H₂O and HCl. The reactions thus result in an effective R鈥搕ricarbaborane cross-coupling. Individual compounds of structure 2 have been purified by chromatography on a silica gel support, using hexane as the mobile phase (R_F = 0.3). Deprotonation agents, such as NEt₃, NaOH, NaH, etc., convert tricarbaboranes 2 into the corresponding conjugated anions [8-R-nido-7,8,9-C₃B₈H₁₀]^{鈭?/sup> (2鈥?/sup>) which were isolated as salts with suitable countercations (for example, Et₃NH+, Tl+, NEt₄+, etc.). The compounds have been characterized by multinuclear (11B, 1H, and 13C) NMR spectroscopy, mass spectrometry, and elemental analyses. The structures of anions [8-R-nido-7,8,9-C₃B₈H₁₀]炉 (where R = C₆H₅, 4-I-C₆H₄ and 1-C₁₀H₇; 2a鈥?/sup>, 2g鈥?/sup>, and 2h鈥?/sup>) and that of the neutral 8-(1-C₁₀H₇)-nido-7,8,9-C₃B₈H₁₁ (2h) have been established by X-ray diffraction analyses.}