Brønsted Acid Catalyzed Intramolecular Hydroarylation of Alkenes to Access Benzylic Quaternary Center Containing Benzocarbocycles
Abstract
Construction of the alkylarenes with benzylic all-carbon quaternary center is an attractive topic within synthetic community due to the synthetic challenge it possesses and the presence of the benzylic quaternary center in natural and synthetic molecules with remarkable chemical as well as pharmaceutical properties. Brønsted acid catalyzed intramolecular hydroarylation of unactivated alkenes is an atom-economic and environmentally friendly straightforward method to obtain benzylic quaternary centers. This research has focused on acid catalyzed intramolecular functionalization of unactivated congested alkenes in which the heteroaromatic ring is linked to the styrene moiety via a quaternary benzylic geminal dimethyl group. The Brønsted acid catalyzed intramolecular reactions of the designed alkenes of this kind produce a variety of synthetically challenging spiroheterocycles bearing vicinal quaternary centers through dearomative spirocyclization at ambient temperature. The seven-membered-ring compounds with benzylic quaternary center are also obtained.