Acid-mediated three-component aza-Diels-Alder reactions of 2-aminophenols under controlled microwave heating for synthesis of highly functionalized tetrahydroquinolines. Part 9: Chemistry of aminophenols

摘要

The aza-Diels-Alder reactions of two 2-aminophenols in combination with six substituted benzaldehydes and two electron-rich cyclic alkenes were investigated under controlled microwave heating. The reactions were carried out in the presence of a catalytic amount of CF3CO2H in MeCN at 60 degrees C for 15 min, affording highly functionalized 8-hydroxy-1,2,3,4-tetrahydroquinolines in 39-59% isolated yields and in 36:64-16:84 diastereomer ratios in favor of the trans isomers. The microwave-heated three-component aza-Diels-Aider reactions completed in significantly reduced reaction time to give the same level of chemical yield and diastereomer ratio obtained from the room temperature reaction. (c) 2006 Elsevier Ltd. All rights reserved.