Reseach on Preparation and Properties of the dpcb Ligand and Their Metal Complexes Containing Various Functional Groups

具有空间保护作用的3,4-二膦环丁烯（以下简称DPCB）具有非常庞大的2,4,6-三-t-丁基苯基（简称Mes^*基团），是一种独特的双齿配体，因为它们具有相对刚性的结构，含有磷-碳π键。我们制备了多种二氯联苯过渡金属配合物，其中一些用作均相催化剂。我们最近制备了1,2-二（2-噻吩基）-3,4-二膦基环丁烯（DPCB-T）和1,2-二（3-噻吩基）-同源物（DPCB-T’），以及一些含有重复单元的聚合物。DPCB- t和DPCB- t都是构建更精细的DPCB衍生物的有希望的构建块，因为在温和的条件下，官能团（在硫原子的a位置）的引入预计很容易进行。事实上，各种DPCB-T衍生物是通过与丁基锂的锂化反应，然后与亲电试剂反应而制备的。通过DPCB-T与丁基锂和碘乙腈的连续反应，得到了更多的o-和二碘-DPCB-T衍生物。然后对碘-DPCB- t衍生物进行进一步转化：引入各种炔基，如三甲基硅乙基、吡啶乙基或azuleny乙基，以得到新的DPCB配体。还制备了一些1,2位含有噻唑基或唑烯基的新型3,4-二膦基环丁烯。此外，还开发了以下新型隔离剂。在开发新型有机磷配体的持续研究过程中，我们对含有2,3-乙烯间隔的配体体系感兴趣。2,3-噻吩间隔剂的优点是：很容易在噻吩环的5位上引入取代基或官能团。这一优势将有助于诸如复杂配体的研究。然后，我们研究了1,4-二（2-乙基-3-噻吩基）苯的制备及其在吡啶配体上的应用，其中二（乙基噻吩基）苯部分作为间隔剂。少

Sterically protected 3,4-diphosphinidenecyclobutenes (hereafter abbreviated to DPCB), bearing an extremely bulky 2,4,6-tri-t-butylphenyl group (abbreviated to the Mes^* group), are unique bidentate ligands of interest, because of their relatively rigid framework containing the phosphorus-carbon π-bond. We have prepared various transition metal complexes of DPCB and some of them were used as homogeneous catalysts. We recently prepared 1,2-di(2-thienyl)-3,4-diphosphinidenecyclobutene (DPCB-T) and 1,2-di(3-thienyI)- congener (DPCB-T'), as well as some polymers bearing repeating unit containing the DPCB-T moiety. Both DPCB-T and DPCB-T are promising building blocks for construction of more elaborate DPCB derivatives, because introduction of functional group (at the position a to the sulfur atom) is expected to be easily performed under mild conditions. In fact, various DPCB-T derivatives were prepared by lithiation with butyllithium followed by reaction with electrophiles. Furthermore, mon … More o-and diiodo-DPCB-T derivatives were obtained by successive reactions of DPCB-T with butyllithium and iodoacetonitrile. Further conversions of the iodo-DPCB-T derivatives were then carried out : Various alkynyl groups, such as trimethylsilylethynyl, pyridylethynyl, or azulenylethynyl, were introduced to give new DPCB ligands. Some novel 3,4-diphosphinidenecyclobutenes, bearing thienyl or azulenyl group at the 1,2-positions, were also prepared. In addition, novel spacer was developed as follows. In the course of our continuing researches on developing novel organophosphorus ligands as mentioned above, we interested in the ligand system containing the 2,3-thienylene spacer. The 2,3-thienylene spacer has an advantage : introduction of substituents or functional groups into the 5-position of the thiophene ring is easy. This advantage will help, for example, researches on sophisticated ligands. We then investigated preparations of 1,4-bis(2-ethynyl-3-thienyl)benzene and its application to pyridine ligands, in which the bis(ethynylthienyl)benezene moiety is incorporated as a spacer. Less