The present invention relates to a number of innovative electrophilic substitution reactions involving 2,5-dithienylpyrrole (2,5-DTP). More specifically, these reactions are used in the synthesis of monomers for preparing functionalized conducting organic polymers.
The electrophilic substitution reactions in this invention are accomplished under conditions not requiring the use of N-1 pyrrole blocking groups to direct reaction at the pyrrole C-3 position. This is because the steric bulk of the 2,5-dithienyl groups prevent N-acylation and therefore direct reactions with electrophiles at the pyrrole C-3 position.
The reaction conditions chosen have also demonstrated a greater regioselectivity towards functionalization at the pyrrole 3-position that the basic reaction conditions suggested in the prior art. This result may be explained by an activation of the pyrrole 3-position towards electrophilic substitution. This is attributed to an electron donating resonance contribution of the 2,5 thienyl groups.
Other advantageous reaction conditions have been discovered which direct electrophilic substitution preferentially at the pyrrole or thiophene groups depending upon the amount of acidic catalyst.
本发明涉及一些涉及 2,5-二
噻吩基
吡咯(2,5-DTP)的创新亲电取代反应。更具体地说,这些反应用于合成制备功能化导电有机聚合物的单体。
本发明中的亲电取代反应是在不需要使用 N-1
吡咯封端基团来引导
吡咯 C-3 位反应的条件下完成的。这是因为 2,5-二
噻吩基团的立体结构阻止了 N-酰化,因此无法在
吡咯 C-3 位与亲电物直接反应。
与现有技术中提出的基本反应条件相比,所选择的反应条件还显示出对
吡咯 3 位官能化的更大区域选择性。这一结果可以通过激活
吡咯 3 位的亲电取代来解释。这归因于 2,5
噻吩基团的电子捐赠共振作用。
我们还发现了其他有利的反应条件,根据酸性催化剂的用量,这些条件可优先在
吡咯或
噻吩基团上引导亲电取代。