Síntese de 3-iodo-4H-calcogenofeno[3,2-b]indol via ciclização eletrofílica mediada por iodo de derivados de alquinil indol

Abstract

The treatment of alkynyl índoles by using iodine with electrophilic source led to 3-iodo-4H-calcogenophene[3,2-b]indoles derivates. Firstly a series of studies were performed variations to obtain the compounds containing a selenium heteroatom in the structure, thus investigating the reaction parameters such as temperature, solvente and proportion of reagentes. The results indicated the best reaction condition using 2-alkynyl indole (0,25 mmol), THF (5ml) iodine (1,1 equiv) at room temperature. By means this methodology the products were obtained in yelds of 39-89%. A second study were performed reporting the products containing a súlfur heteroatom in the structure. Thus, the best reaction conditions studied used alkynyl indole (0,25 mmol), etanol (5 mL), iodine (3 equiv.), ethyl disulfide ( 3 equiv.) at 70 °C for 3 hours. The use iodine as an electrophilic source in additon to demonstrating efficiency as triple bond activation agente is efficient in the cyclization process, making the metodology more efficient for both other cyclizations and future functionalisations. The insertion of a halogen atom in a strategy position in the molecule allows the synthesis of new heterocycles of greater complexity through coupling reactions with metals such as Ullmann type complings.