Synthesis of Phenylacetylene Dendrimers Having Sterically Congested Diazo Units and Characterization of Their Photoproducts
作者:Tetsuji Itoh、Toshiyuki Maemura、Yusuke Ohtsuka、Yoshiyuki Ikari、Holger Wildt、Katsuyuki Hirai、Hideo Tomioka
DOI:10.1002/ejoc.200400123
日期:2004.7
6-dibromo-4-ethynylphenyl)diazomethane (2a). The diazomethane 2a was used as a starting compound for synthesis of phenylacetylene dendritic molecules having peripheral diazo groups by the convergent method. Thus, tridendrons with peripheral groups bearing 3 (3a), 6 (6a), and 12 (8a) diazo units were prepared, in which diazo groups were introduced so as to generate polycarbenes in a ferromagnetic fashion. In order
发现化合物 (4-叔丁基-2,6-二甲基苯基)(2,4,6-三溴苯基)重氮甲烷 (1a) 是持久性三线态卡宾的前体,被发现足够稳定,可以在 Sonogashira 偶联反应条件下存活,从而得到(4-叔丁基-2,6-二甲基苯基)(2,6-二溴-4-乙炔基苯基)重氮甲烷(2a)。重氮甲烷2a用作通过收敛法合成具有外围重氮基团的苯乙炔树枝状分子的起始化合物。因此,制备了具有带有 3 (3a)、6 (6a) 和 12 (8a) 个重氮单元的外围基团的三叉树,其中引入了重氮基团以便以铁磁方式生成聚卡宾。为了表征由这些树枝状聚合物的光解产生的卡宾的自旋状态,测量了光产物的磁化率。虽然三(重氮)化合物的光产物数据拟合为 S = 2.5,但六和十二(重氮)化合物光产物的数据拟合为 S = 1.62,该值远小于理论预测值甚至比三碳烯还要小。结果根据不相交-非不相交概念进行解释。(© Wiley-VCH Verlag