Quinazolinones and their derivatives have drawn much attention owing to their various pharmacological properties. They exhibit diverse biological properties like, antimicrobial, [1][2][3] antiviral, 4) anticancer, 5) anticonvulsant, 6) CNS depressant 7) and antihypertensive activity. 8) Amongst these, C-2 and N-3 disubstituted quinazolines with aryl and heteroaryl groups at N-3 position have shown enhanced anti-inflammatory activity as a result of their nitric oxide inhibitory activities.
9)A good deal of research has been carried out on the coordinating behavior of 2,3-disubstituted quinazolin-4(3H)-ones which offer various potential donor sites. [10][11][12][13][14][15] In comparison, 2,3-disubstituted 1,2-dihydroquinazolinones and their metal complexes are not much explored. We have recently reported the synthesis of 1,2-dihydroquinazolinones by the condensation of 2-aminobenzoylhydrazide with aryl and heteroaryl aldehydes and their chelating behavior towards transition and inner transition metal ions. [16][17][18][19][20][21][22] Their antimicrobial potency is also tested against different bacterial and fungal strains. Our continued research in this perspective resulted in a new approach, in which 2-aminobenzoylhydrazide is converted to hydrazone in the first step. The reaction of this hydrazone with aromatic aldehydes results in the formation of biologically active 1,2-dihydroquinazolinones, with different substituent at C-2 and N-3 positions.Aroylhydrazones of salicylaldehyde, which typically act as tridentate planar chelate coordinating through phenolic oxygen, amide oxygen and imine nitrogen (Chart 1a) are known for their interesting biological activities.23) Keeping the framework of coordinating sites of aroylhydrazones intact, we have designed quinazoline analogue (Chart 1b) of aroylhydrazone of o-hydroxyacetophenone which is structurally similar with aroylhydrazones of salicylaldehyde. Recent investigation show that coordination of organic molecules and anti-inflammatory drugs with Co(II), Ni(II), Cu(II), Fe(II) and Zn(II) metal ions resulted in the enhancement of their activity. [24][25][26] Thus, the present article charts the progress of our methodology in the synthesis of new 1,2-dihydroquinazolin-4(3H)-one derivative viz., 2-hydroxy-2-ethyl-(3-carboxylideneamino)-3-(2-(4-methyl-phenyl))-1,2-dihydroquinazolin-4(3H)-one (HECMDQ) (C1) with different substituent at C-2 and N-3 positions and its coordinating behavior towards Co(II), Ni(II), Cu(II) and Zn(II) ions. The results of analgesic activity are impressive and perhaps suggestive of future success.
ExperimentalMaterials Methylanthranilate (S.D. Fine Chemicals, India), hydrazinehydrate (Spectrochem, India) o-hydroxyacetophenone (Himedia, India), pmethylbenzaldehyde (Spectrochem, India) and metal(II) chlorides used in the present study were of AR grade and used as supplied. All the solvents were distilled before use. o-Aminobenzoylhydrazide 27) and o-hydroxyacetophenone-o-aminobenzoylhydrazone 28) were prepared following the literature procedures.P...