Multicomponent reaction 1 DFT Natural products Heteropoly acids Heteropolyacid Keggin Total synthesis 2 2-Aminobenzimidazole 2-Bromoacetophenones catalyst-free reaction 2-Chloroquinoline-3-carboxaldehydes 2-Formylindole 2-amino-4H-chromenes 2-b]pyrroles 2-chloro-3-formyl quinolone 2-formylindole 3 H)-diones 3-Cyclohexanediones 3-formyl-2-mercaptoquinolines 3-indandione 4-Dihydro-3H-pyrazol-3-ones 4-Dihydropyridines 4-conjugate addition reaction 5-(1 H 5-diones Adduct Asymmetric synthesis Biologically active compounds Carbon–carbon bond Carbon–carbon bond formation Catalyst Chiral auxiliary Chromenopyrimidine Chromenopyrimidine-2 Computational Condensation Cross-coupling reaction Cyclization Density functional theory Diketene Dimedone Dimedone-based enaminones ECD spectra Fluorescent Grignard reagent H5BW12O40 Halloysite Hantzsch reaction Hybrid