Switchable Synthesis of Spirodihydroindolizines and Indolizines from Aurones and Pyridin-2-yl Active Methylene Compounds
Quan Liu, Feng Wang, Zeng‐Yang He, Hui Zhang, Jiarong Wang, Qinghai Li, Ze Zhang, Hui Xu
Abstract
A novel and flexible domino reaction of aurones with pyridin-2-yl active methylene compounds promoted by I 2 /BF 3 has been developed to afford spirodihydroindolizines and indolizines in a controllable manner. When the reaction was performed in 1,2-dichloroethane at 80 °C, a variety of spirodihydroindolizines were obtained, whereas it almost exclusively provided a series of indolizines when the reaction was performed in a mixed solvent of 1,2-dichloroethane and N, N -dimethylformamide at a relatively higher temperature of 100 °C. Being metal-free, excellent product selectivity, high atom economy, good functional group tolerance, and feasibility for large-scale synthesis are the salient features of the developed methodology.