Beyond A Protecting Reagent: DMAP-catalyzed Cyclization Of Boc-anhydride With 2-alkenylanilines

Quinoline is a class of important structural motif,and has been widely exist in a number of natural products with pharmacological activity.It has been found important applications in organic chemistry.In recent years,many methods involving metal catalysis or acid or base catalysis were reported by literature.These methods feature atom economy and environmental friendly compared to traditional processes.Herein,we disclosed a DMAP?4-dimethylaminopyridine?catalyzed reaction to synthesize quinoline compounds.Features of this raction include: 1)formation of isocyanate;2)nonmental catalysis and mild conditions;3)Boc₂O?di-tert-butyl dicarbonate?was the carbon source.We conducted the reaction with 2-amino styrene 146 as substrates,DMAP as catalyst,and reacted with Boc₂ O in dichloromethane,a series of quinoline derivatives bearing different subsitutions were synthesized.All compounds have been characterized by 1H NMR,13 C NMR and HRMS.The structure of compound 147 a was also confirmed by X-ray crystallography.A plausible mechanism to synthesize quinoline has been proposed.It is assumed isocyanate was the intermediate.In addition,we explored the application of the products.The 2-quinolone and 2-halo quinoline were obtained via hydrolysis or derivatization.