Compounds containing the indole nucleus show an extensive assortment of biological and pharmacological activities, including analgesic, antiallergic, antibacterial, anti-HIV, antitumor, and antioxidant properties [1,2]. Recently, the synthesis and anticancer properties of alkaloids with dimeric indole scaffolds were reported [3]. Therefore, our interest was focused on the study of the oligomerization reactions of 4-, 6- and 7- substituted indoles with electron donor groups, i.e. methoxy group, and electron withdrawing groups, i.e. nitrile group, using a Lewis acid (bismuth chloride). From our results, we concluded that indole oligomerization is sensitive to the substituent on the heterocycle. Both the substituent position and the inductive effects of the substituents, determine which products and in which ratio they are formed. We were also able to propose possible mechanisms for the reaction that can explain the different products obtained for each substrate. .

Dirección General de Investigación e Innovación de la Comunidad de Madrid y Fondo Europeo de Desarrollo Regional (B2017/BMD-3827); Ministerio de Ciencia, Innovación y Universidades, Agencia Estatal de Investigación y FEDER (SAF2015-64948-C2-1-R and RTI2018-093955-B-C21); Consejo Superior de Investigaciones Científicas (JAE-Intro18_EX-0264 a I.S.-P.)