Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Hlavní 1001, CZ-250 68 Řež, Czech Republic.
Dalton Trans. 2014 Apr 7;43(13):5106-20. doi: 10.1039/c3dt52870g.
Low temperature reactions of lithiated cobalt bis(1,2-dicarbollide)(1-) (1⁻) in DME with carbon dioxide leads to the substitution of 1⁻ at the C-atoms by carboxy function(s). This results in a good yield formation of monosubstituted and disubstituted products of formulations (1-HOOC-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co) (2⁻) and (HOOC)2-(1,2-C2B9H10)2-3,3'-Co (3a,b⁻), respectively. Indeed, the latter compound is in fact a mixture of two diastereoisomers, denoted here as 1,1'-anti (3a⁻) and 1,2'-syn-isomer (3b⁻), from which only the former major species (3a⁻) could be isolated in pure form. Considerations about stereochemistry of these species are supported by geometry optimizations and calculations of (11)B NMR shifts at the GIAO-DFT level. In addition, three monocarboxylic acids with three different linear spacers between the carboxy groups and the cage are reported. The first one of the formula (1-HOOC-CH2-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co (5⁻) results in a lithiation followed by reaction with BrCH2COOEt and hydrolysis of the respective ethyl ester (4⁻). Another one with ethylene chain (1-HOOC-(CH2)2-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co (6⁻) was prepared by the oxidation of a hydroxypropyl derivative of the ion 1⁻. The sole representative of B-substituted species of the formulation 8-(HOOC-CH2-O-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co (7⁻) is prepared by alkylation of the known 8-hydroxy derivatives of the ion 1⁻ by BrCH2COOEt and alkaline hydrolysis. A synthetic route to active nitrofenyl esters (8⁻, 9⁻ and 10⁻) is described here based on the respective acids 5⁻ to 7⁻. As verified, the nitrophenyl esters provide easy access to the formation of amidic bonds between the boron cage and organic primary amino functions. Examples of compounds containing butylamide or benzylamide (1-RNHOC-(CH2)n-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co (n = 1,2; R = Bu 11a,b⁻, R = Bn: 12a,b⁻) end group are described. Also the possibility of inter-connecting two clusters of the anion 1⁻ via the amidic bond is shown in derivative (13⁻). These methods are applicable in the synthesis of a variety of functional molecules, particularly those applicable in drug design, surface modifications, and material science.
在 DME 中，与二氧化碳一起作用，锂化的二(1,2-二碳硼烷)(1⁻)的低温反应导致 1⁻在 C 原子处被羧基官能团取代。这导致单取代和二取代产物的良好产率形成，其配方为(1-HOOC-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co) (2⁻)和(HOOC)2-(1,2-C2B9H10)2-3,3'-Co (3a,b⁻)。事实上，后者化合物实际上是两种非对映异构体的混合物，这里表示为 1,1'-anti (3a⁻)和 1,2'-syn-异构体(3b⁻)，其中只有前一种主要物质(3a⁻)可以以纯形式分离出来。这些物质的立体化学的考虑得到了 GIAO-DFT 水平的(11)B NMR 位移的几何优化和计算的支持。此外，还报道了三种具有羧基和笼之间三个不同线性间隔的单羧酸。第一个具有公式(1-HOOC-CH2-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co (5⁻)的羧酸是通过锂化然后与 BrCH2COOEt 反应以及相应的乙酯(4⁻)的水解得到的。另一个具有乙烯链的(1-HOOC-(CH2)2-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co (6⁻)是通过离子 1⁻的羟丙基衍生物的氧化制备的。8-(HOOC-CH2-O-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co (7⁻)的 B 取代物的唯一代表是通过 BrCH2COOEt 和碱性水解对已知的 8-羟基离子 1⁻进行烷基化制备的。本文描述了一种基于酸 5⁻至 7⁻的活性硝基苯酯(8⁻、9⁻和 10⁻)的合成路线。经验证，硝基苯酯为硼笼与有机伯氨基官能团之间形成酰胺键提供了便利途径。含有丁酰胺或苄酰胺(1-RNHOC-(CH2)n-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co (n = 1,2; R = Bu 11a,b⁻，R = Bn: 12a,b⁻)端基的化合物的实例也有描述。此外，通过酰胺键还可以显示出阴离子 1⁻的两个簇之间的相互连接的可能性，如图(13⁻)所示。这些方法适用于多种功能分子的合成，特别是那些适用于药物设计、表面修饰和材料科学的功能分子。
