Synthesis of 3,4-Dihydropyrazino[1,2-a]indol-1(2H)-Ones by Cascade Addition-Cyclization Reactions from Vinyl Selenones

Recently vinyl selenones have been discovered as excellent substrates to synthesize indole derivatives in an cost-inexpensive and eco-friendly reaction. Herein we describe the synthesis of 3,4-dihydropyrazino[1,2-a]indol-1(2H)-ones, which attracted the attention of medicinal chemists thanks to their important biological activities such as antifungal, antihistaminergic and anti-serotoninergic. The reaction takes place via a Michael addition-cyclization cascade starting from vinyl selenones and (1H-indol-2yl)carboxamides using as base potassium hydroxide.