Autocatalytic Green Synthesis of Imines in Traceless Medium

Abstract

For the first time, condensations of amines with carbonyl compounds have been performed in supercritical carbon dioxide (sc‐CO2). The reactions with aldehydes or active ketones proceed at moderate temperatures (35–55 °C) without use of external catalysts. The process is autocatalytic: it is accelerated by the carbonic acid generated in situ by interaction between the released water and the CO2 medium. The imine products were obtained in high yields in a crystalline form and did not require further purification. The one‐pot transfer hydrogenation and [4+2] cycloaddition reactions performed in the CO2 medium have uncovered attractive prospects for facile green synthesis of more complex and valuable compounds from the generated in situ imine products.