Synthesis of 5,6-Dihydropyrazolo[5,1-<i>a</i>]isoquinolines through Tandem Reaction of <i>C</i>,<i>N</i>-Cyclic Azomethine Imines with α,β-Unsaturated Ketones

Abstract

An innovative and efficient approach has been developed for the synthesis of 5,6-dihydropyrazolo[5,1-a]isoquinolines. This one-pot tandem reaction involves the reaction of C,N-cyclic azomethine imines with α,β-unsaturated ketones, using K2CO3 as the base and DDQ as the oxidant. The process results in functionalized 5,6-dihydropyrazolo[5,1-a]isoquinolines with good yields. This convenient one-step method encompasses a tandem [3 + 2]-cycloaddition, detosylation, and oxidative aromatization.

Keywords

• fused pyrazoles
• nitrogen heterocycles
• <i>C</i>,<i>N</i>-cyclic azomethine imines
• cycloaddition
• tandem reaction