Intramolecular imino-Diels–Alder reactions in [bmim]BF4 ionic medium: Green protocol for the synthesis of tetrahydrochromanoquinolines

2-Azadienes derived in situ from aryl amines and O-prenyl derivatives of salicylaldehydes under intramolecular [4 + 2] imino-Diels–Alder reaction, in an air and moisture stable [bmim]BF4 ionic medium afford tetrahydrochromanoquinolines in high to quantitative yield. This new protocol offers significant advantages over reported methods which include mild reaction conditions, high conversions, enhanced reaction rates and recyclability of ionic liquids.

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