Reações de ciclização de N,N-Dimetil-2-((Organoselenil)etinil)anilinas promovidas por iodo molecular

Abstract

This work reports the studies for the development of a synthetic methodology for the preparation of 3-iodo-1-methyl-2-(organochalcogenyl)-1H-indoles, which have an organochalcogen group directly bonded to the C-2 position of the indole nucleus. through intramolecular electrophilic cyclization reactions of N,N-dimethyl-2- ((organochalcogenyl)ethynyl)anilines, using molecular iodine as a cyclization promoting agent, emphasizing the use of mild and ecologically less harmful reaction conditions. Therefore, an extensive bibliographic research was carried out in order to get data that would provide theoretical support for the research. Thus, a literature review has made regarding the synthetic methodologies for the preparation of indole derivatives through intramolecular electrophilic cyclization reactions mediated by iodine reagents, especially involving the use of alkynyl substrates. Based on previously described conditions, the 4-chloro-N,N-dimethyl-2-((phenylselenyl)ethynyl)aniline was subjected to the cyclization reaction using molecular iodine and dichloromethane as solvent, and it was possible to obtain 5- chloro-3-iodo-1-methyl-2-(phenylselenyl)-1Hindole in 55% yield. In order to increase the efficiency of the cyclization process, studies were started to evaluate and define the best reaction parameters, such as temperature, atmosphere, time, amount of molecular iodine, and the nature of the solvent. To carry out these studies, which are still in progress, it was decided to use the N,N-dimethyl-2-((phenylselenyl)ethynyl)aniline as a standard substrate due to the absence of a substituent on the benzene ring attached to the nitrogen (in order to minimize a possible electronic influence on the cyclization process). The first tests performed with this substrate proved to be absolutely promising, since the cyclization product 3-iodo-1-methyl-2-(phenylselenyl)-1H-indole was isolated in 80% yield, in relatively short reaction time (1h).