“…According to the importance of the mentioned pyrimido[4,5- b ]quinolines, various catalysts were reported for the multi-component synthesis of pyrimido[4,5- b ]quinolines such as [TSSECM], SBA-15/PrN(CH 2 PO 3 H 2 ) 2 , [H 2 -DABCO][ClO 4 ] 2 , nano-[Fe 3 O 4 @SiO 2 / N -propyl-1-(thiophen-2-yl)ethanimine][ZnCl 2 ], nano-[Fe 3 O 4 @-SiO 2 @R-NHMe 2 ][H 2 PO 4 ], Fe 3 O 4 @Cellulose sulfuric acid, N , N -diethyl- N -sulfoethanaminium chloride, [bmim]Br, glycolic acid-supported cobalt ferrite, nanocrystalline MgO, [C 4 (DABCO) 2 ]·2OH, and agar-entrapped sulfonated DABCO . However, most of the proposed methods are performed by acidic and expensive catalysts.…”