Alkylation of 3-Formylquinoline-2-One With Alkenyl(alkynyl) Bromides

Functional and condensed quinolin-2-one derivatives exhibit a wide range of biological activity. The presence of an aldehyde group and modification at position 1 or 2 of quinolin-2-one expand the searching for new biologically active compounds. One of the directions of such modification is the annulation of an additional azaheterocycle to quinoline. In this work, the interaction of unsaturated alkyl halides (4-bromobut-1-ene, 5-bromopent-1-ene, 5-bromopent-1-yne) with 3-formylquinolin-2-one was investigated. The reaction was carried out in the presence of dimethylformamide using sodium hydride at room temperature or heating to 80°C for 8 hours. It was shown that under the found conditions, non-regioselective alkylation occurs with the formation of a mixture of O- and N-alkylation isomers. According to spectral data, the ratio of alkylation products depends on the alkylating agent. Thus, in case of using 3-formylquinolin-2-one, 4-bromobut-1-ene or 5-bromopent-1-yne, a mixture of O- and N-alkyl quinolines is formed in a ratio of 1:1.5, and in case of 5-bromopent-1-ene - 2:1. N-butenyl-3-formylquinolin-2-one was isolated by fractional crystallization, and in other cases, mixtures with minor amounts of one of the isomers were isolated.