obtained starting from easily available materials and involving the cyclization of diarylamines. The first step of the preparation consists in a SNAr reaction between a para substituted aniline and a chloro- (or bromo)-dinitrobenzene. This nucleophilicsubstitution has been found to be hindered by the steric effect of a methyl group, explained in terms of inhibition of resonance and confirmed by X-ray determination
3-氰基咔唑,是吡啶并[4,3- b ]咔唑全合成中的关键中间体,已从易于获得的材料开始,涉及二芳基胺的环化反应。制备的第一步在于对位取代苯胺与氯-(或溴)-二硝基苯之间的S N Ar反应。已经发现这种亲核取代被甲基的空间效应所阻碍,这在抑制共振方面得到了解释,并通过X射线测定得到了证实。