A New Method For The Synthesis Of 2-vinylquinolines

2-vinylquinolines are not only ubiquitous structural motifs in biologically relevant molecules, but also valuable intermediates in organic synthesis and drug discovery. But all reported methods possess some shortcomings, such as low yield, harsh reaction conditions, numerous steps, and the use of organometallic compounds, etc. Therefore, it is necessary to develop a simple, efficient and catalyst-free method to synthesize 2-vinylquinolines.In this thesis, a brief introduction of the Mannich reaction and conventional methods for the synthesis of 2-vinylquinolines was first reviewed. Then the advantages and shortcomings of all these reported methods for the synthesis of 2-vinylquinolines were surveyed in details. The research work of this thesis was based on classical Mannich reaction, after rational design we have developed a simple catalyst-free method for the synthesis of 2-vinylquinolines. The method is that 2-methyIquinolines, formaldehyde solution and diethylamine hydrochloride react together with 5 mol% Et3N in dioxane at 101 ℃, then we can directly separate 2-vinylquinolines with high yields. A key step for this method is instantaneous hydrogen transfer via a six-membered ring intermediate, inducing Mannich base’s directly deamination reaction. This reaction strategy tolerates a broad substrate scope and provides a high-efficient way to synthesize 2-vinylquinolines with adequate yields.