Electrophilic nitration, formylation and acetylation of the title heterocycle 1 were studied. Monosubstitution proceeds preferentially in position 2 and to a lesser extent in position 4. Lowering the reaction temperature substantially increases regioselectivity of nitration and acetylation. Substitution reactions of the 2-substituted derivatives of 1 led to the corresponding 2,7-disubstituted derivatives as major products. Formation of other regioisomers was also observed. Metallation of 1 with butyllithium preferably proceeds in position 1; subsequent reaction with N,N-dimethylformamide, carbon dioxide or iodine gives rise to corresponding 1-substituted derivatives. Long-chain 2,7-disubstitued derivatives exhibit liquid-crystalline properties.
研究了对位杂环1的亲电取代硝化、甲酰化和乙酰化。单取代反应优先在2位发生,其次在4位发生。显著降低反应温度可以增加硝化和乙酰化的区域选择性。对1的2-取代衍生物的取代反应导致了相应的2,7-双取代衍生物作为主要产物。还观察到其他区异构体的形成。用丁基锂对1进行金属化反应时,优先在1位发生;随后与N,N-二甲基甲酰胺、二氧化碳或碘反应,产生相应的1-取代衍生物。长链的2,7-双取代衍生物表现出液晶性质。