Kultyshev Roman G, Liu Shengming, Leung Hoitung T, Liu Jianping, Shore Sheldon G
Department of Chemistry, The Ohio State University, Columbus, OH 43210, USA.
Inorg Chem. 2003 May 19;42(10):3199-207. doi: 10.1021/ic020600u.
Two series of compounds, 9-X-1,7-(Me(2)S)(2)B(12)H(9) and 9,10-X(2)-1,7-(Me(2)S)(2)B(12)H(8) (X = Cl, Br, I), have been synthesized from reactions of 1,7-(Me(2)S)(2)B(12)H(10) with various halogenating reagents. In addition, reactions of 1,7-(Me(2)S)(2)B(12)H(10) with 2,4-(NO(2))(2)C(6)H(3)SCl and PhSeBr resulted in 9-(2',4'-(NO(2))(2)C(6)H(3)S)-1,7-(Me(2)S)(2)B(12)H(9) and 9,10-(PhSe)(2)-1,7-(Me(2)S)(2)B(12)H(8), respectively. X-ray studies of the dibromo, monoiodo, and aryl thioether derivatives show that electrophilic substitution in 1,7-(Me(2)S)(2)B(12)H(10) takes place at positions 9 and 10, as in the case of the meta-carborane 1,7-C(2)B(10)H(12). From 1,12-(Me(2)S)(2)B(12)H(10) the halides 2-X-1,12-(Me(2)S)(2)B(12)H(9) (X = Br, I) were prepared. For both 1,7- and 1,12-(Me(2)S)(2)B(12)H(10) the best iodination results were obtained using iodine monochloride in refluxing acetonitrile. In the presence of 5 mol % (PPh(3))(2)PdCl(2) the iodides 9-I-1,7-(Me(2)S)(2)B(12)H(9), 2-I-1,12-(Me(2)S)(2)B(12)H(9), and 9,10-I(2)-1,7-(Me(2)S)(2)B(12)H(8) react with RMgX (R = Me, Ph, Bn; X = Cl, Br) in THF to yield the corresponding B-alkyl- and B-aryl-substituted products in good yields without using CuI as a cocatalyst. The bromo derivative 9-Br-1,7-(Me(2)S)(2)B(12)H(9) did not react under similar conditions. No interference from the nearby Me(2)S substituent was observed in palladium-catalyzed substitution of iodide in 2-I-1,12-(Me(2)S)(2)B(12)H(9). Presumably due to the intramolecular activation of an aryl C-H bond of the benzyl substituent in the intermediate palladium complex, the yield of 9,10-Bn(2)-1,7-(Me(2)S)(2)B(12)H(8) was significantly lower than those of the dimethyl and diphenyl derivatives. The molecular structures of 9-R-1,7-(Me(2)S)(2)B(12)H(9) (R = Ph, Bn) and 2-Bn-1,12-(Me(2)S)(2)B(12)H(9) were obtained by single-crystal X-ray analysis.
通过1,7-(Me₂S)₂B₁₂H₁₀与各种卤化试剂的反应，合成了两个系列的化合物，即9-X-1,7-(Me₂S)₂B₁₂H₉和9,10-X₂-1,7-(Me₂S)₂B₁₂H₈（X = Cl、Br、I）。此外，1,7-(Me₂S)₂B₁₂H₁₀与2,4-(NO₂)₂C₆H₃SCl和PhSeBr的反应分别生成了9-(2',4'-(NO₂)₂C₆H₃S)-1,7-(Me₂S)₂B₁₂H₉和9,10-(PhSe)₂-1,7-(Me₂S)₂B₁₂H₈。二溴、一碘和芳基硫醚衍生物的X射线研究表明，1,7-(Me₂S)₂B₁₂H₁₀中的亲电取代发生在9位和10位，就像间位碳硼烷1,7-C₂B₁₀H₁₂的情况一样。由1,12-(Me₂S)₂B₁₂H₁₀制备了卤化物2-X-1,12-(Me₂S)₂B₁₂H₉（X = Br、I）。对于1,7-和1,12-(Me₂S)₂B₁₂H₁₀，在回流乙腈中使用一氯化碘可获得最佳碘化结果。在5 mol% (PPh₃)₂PdCl₂存在下，碘化物9-I-1,7-(Me₂S)₂B₁₂H₉、2-I-1,12-(Me₂S)₂B₁₂H₉和9,10-I₂-1,7-(Me₂S)₂B₁₂H₈在四氢呋喃中与RMgX（R = Me、Ph、Bn；X = Cl、Br）反应，无需使用碘化亚铜作为助催化剂即可高产率地生成相应的B-烷基和B-芳基取代产物。溴衍生物9-Br-1,7-(Me₂S)₂B₁₂H₉在类似条件下不反应。在2-I-1,12-(Me₂S)₂B₁₂H₉的钯催化碘取代反应中，未观察到附近的Me₂S取代基产生干扰。推测由于中间体钯配合物中苄基取代基的芳基C-H键的分子内活化作用，9,10-Bn₂-1,7-(Me₂S)₂B₁₂H₈的产率明显低于二甲基和二苯基衍生物。通过单晶X射线分析获得了9-R-1,7-(Me₂S)₂B₁₂H₉（R = Ph、Bn）和2-Bn-1,12-(Me₂S)₂B₁₂H₉的分子结构。
