Oligomerizations of o-Diisocyanobenzenes by Organometallic Compounds - Synthesis of Functional Nitrogen-Containing Aromatic Polymers

异氰化物与有机锌的单金属化研究了各种异氰化物与二烷基锌的反应，发现芳香族异氰化物插入二烷基锌的锌-碳键中，生成[1-（芳基亚氨基）烷基]锌，而脂肪族异氰化物则不发生反应。[1-（芳基亚氨基）烷基]锌在催化量的过渡金属催化剂（1- 2mol%）存在下与芳香族碘化物反应，生成相应的N-芳基芳香族亚胺。邻二异氰基芳烃与格氏试剂反应合成喹喔啉低聚物1，2-二异氰基-3，4，5，6-四甲基苯与格氏试剂反应，发生芳构化反应，生成各种喹喔啉低聚物。喹喔啉骨架是通过两个邻位异氰基连续插入到碳-镁键中而规则地构建的。这些低聚物通过硅胶上的制备型TLC和/或聚苯乙烯凝胶上的循环HPLC分离和离析。喹喔啉低聚物的紫外光谱揭示了它们的结构特征;喹喔啉三聚物在260和280 nm处显示出两个吸收峰，分别归属于单个孤立的喹喔啉发色团和共轭的喹喔啉发色团。四聚体和五聚体也在与三聚体相同的位置显示吸收。这可能表明，在聚合物链中超过三个连续的喹喔啉环上的有效共振共轭可能受到空间位阻的抑制。

Mono-metallation of an Isocyanide with an Organozinc The reaction of a variety of isocyanides with dialkylzinc was examined and it was found that aromatic isocyanides underwent insertion into zinc-carbon bond of dialkylzinc to give [1- (arylimino)alkyl]zinc, whereas aliphatic isocyanides did not react at all. Treatment of [1- (arylimino)alkl]zinc with aromatic iodide in the presence of a catalytic amount of transition metal catalyst (1-2 mol%) produced the corresponding N-aryl aromatic imine.Synthesis of Quinoxaline Oligomers by Reaction of o-Diisocyanoarene with Grignard Reagent The reaction of 1,2-diisocyano-3.4,5,6-tetramethylbenzene with Grignard reagents resulted in aromatization to give a variety of quinoxaline oligomers. The quinoxaline skeleton was regularly constructed by successive insertion of the two ortho isocyano groups into carbon- magnesium linkage. These oligomers are separated and isolated by preparative TLC on silica gel and/or recycling HPLC on polystyrene gel. UV spectra of the quinoxaline oligomers revealed their structural feature; quinoxaline trimer showed two absorptions at 260 and 280 nm, which can be ascribed to single isolated quinoxaline chromophore and conjugated quinoxaline chromophore, respectively. Tetramer and pentamer also showed the absorption at the same positions as trimer. This may indicate that an effective resonance conjugation over more than three sequential quinoxaline rings in the polymer chain may be inhibited by steric hindrance.