Green and complementary regioselective synthesis of 3-(1 –substituted pyrazol-3(or 5)-yl)indoles from β-ethyltho-β-indolyl-α,β-unsaturated ketones in water

Abstract

Eco-friendly and practical methods for the complementary regioselective synthesis of 3-(1-substituted pyrazol-3-yl) indoles and 3-(1-substituted pyrazol-5-yl) indoles, from DBSA-mediated regioselective cyclocondensation reaction of β-ethyltho-β-indolyl-α, β-unsaturated ketones and monosubstituted hydrazines in water through simply varying the appropriate reaction way, had been developed. The methods not only efficiently avoided the use of organic solvent but also exhibited attractive characteristics such as operational simplicity, broad substrate scope, easy separation of products and ease of scale-up.