New basic ionic liquid from ethan-1,2-diyl bis (hydrogen sulfate) and DBU (1,8-diazobicyclo[5.4.0]undec-7-ene) as an efficient catalyst for one-pot synthesis of xanthene derivatives

Abstract

For the first time a new basic ionic liquid from ethan-1,2-diyl-bis (hydrogen sulfate) and 1,8-diazobicyclo[5.4.0]undec-7-ene was suggested. The catalytic activity of the new ionic liquid was tested for synthesis of xanthene derivatives by condensation of aldehydes with i) dimedone ii) β-naphthol iii) 2-hydroxynaphthalene-1,4-dione iv) dimedone and β-naphthol v) 2-hydroxynaphthalene-1,4-dione and dimedone vi) β-naphthol and 2-hydroxynaphthalene-1,4-dione. This approach is a clean, environmentally friendly and convenient work up protocol. The new ionic liquid is an effective and inexpensive catalyst that could easily be recycled and reused five times without significant loss of catalytic activity.