Michael addition to 3-(2-nitrovinyl)indoles – route toward aliphatic nitro compounds with heterocyclic substituents

Abstract

Synthetic approach toward indole derivatives bearing 2-nitroethyl group and polar azole moiety has been developed. This method involves conjugate addition of 1,3-dicarbonyl compounds to 3-(2-nitrovinyl)-1H-indoles followed by cyclocondensation with hydrazine or hydroxylamine to furnish pyrazole or isoxazole ring. Application of microwave activation allows to obtain the target indole derivatives in short time and avoid protection of indole nitrogen atom