Expeditious synthesis of 5,6,7,8-tetrahydro-imidazo[1,2-a]pyrimidin-2-ones and 3,4,6,7,8,9-hexahydro-pyrimido[1,2-a]pyrimidin-2-ones

Synthetic approaches and functionalizations of imidazo[1,2-a]pyrimidines: an overview of the decade

This review gives an overview to the synthesis of the imidazo[1,2-a]pyrimidines on the basis of multicomponent reactions, condensation reactions, intramolecular cyclizations etc. along with its reactivity at 3-position.

Tandem reaction of Morita–Baylis–Hillman alcohols derived from acrylic nitrile with 2-aminobenzimidazole in ionic liquid [BMIM]Cl/H2O

The tandem reaction of Morita–Baylis–Hillman (MBH) alcohols 1a–1l derived from acrylic nitrile with 2-aminobenzimidazole (2) in ionic iquid (IL) [BMIM]Cl/H2O without additional catalyst was developed for the efficient synthesis of benzimidazol[1,2-a]pyrimidin-7(8H)-imine compounds. The tandem reaction included aza-Michael addition and intramolecular addition of an amino group to the cyano group in one pot. The combination of ionic liquid and water was found to be the best reaction medium, which played a role for accelerating the tandem reaction.

In silico screening, structure-activity relationship, and biologic evaluation of selective pteridine reductase inhibitors targeting visceral leishmaniasis

In this study we utilized the concept of rational drug design to identify novel compounds with optimal selectivity, efficacy and safety, which would bind to the target enzyme pteridine reductase 1 (PTR1) in Leishmania parasites. Twelve compounds afforded from Baylis-Hillman chemistry were docked by using the QUANTUM program into the active site of Leishmania donovani PTR1 homology model. The biological activity for these compounds was estimated in green fluorescent protein-transfected L. donovani promastigotes, and the most potential analogue was further investigated in intracellular amastigotes. Structure-activity relationship based on homology model drawn on our recombinant enzyme was substantiated by recombinant enzyme inhibition assay and growth of the cell culture. Flow cytometry results indicated that 7-(4-chlorobenzyl)-3-methyl-4-(4-trifluoromethyl-phenyl)-3,4,6,7,8,9-hexahydro-pyrimido[1,2-a]pyrimidin-2-one (compound 7) was 10 times more active on L. donovani amastigotes (50% inhibitory concentration [IC(50)] = 3 μM) than on promastigotes (IC(50) = 29 μM). Compound 7 exhibited a K(i) value of 0.72 μM in a recombinant enzyme inhibition assay. We discovered that novel pyrimido[1,2-a]pyrimidin-2-one systems generated from the allyl amines afforded from the Baylis-Hillman acetates could have potential as a valuable pharmacological tool against the neglected disease visceral leishmaniasis.