Preparation and characterization of [H2-DABCO][ClO4]2 as a new member of DABCO-based ionic liquids for the synthesis of pyrimido [4,5-b]-quinoline and pyrimido[4,5-d]pyrimidine derivatives

[H-2-DABCO][ClO4](2), as a novel DABCO-based ionic liquid, has been synthesized, characterized, and used as an affordable and recyclable catalyst in the synthesis of pyrimido [4,5-b]-quinoline and pyrimido [4,5-d]pyrimidine derivatives. The procedure shows several advantages over the previous methods such as simplicity, high yields, short reaction times, easy work-up, and use of a non-metal catalyst. Moreover, this paper virtually debates the impact of anions and cations on moisture-resistant property and catalytic activity in DABCO-based ionic liquids through the comparison of [DABCO](SO3H)(2)(Cl)(2), [DABCO](-SO3H)(2)(HSO4)(2), [H-2-DABCO][H2PO4](2), [H-2-DABCO][HSO4](2), and [H-2-DABCO][ClO4](2). (C) 2018 Elsevier B.V. All rights reserved.