No abstract

A series of methyl 2-(2-(2-arylquinazolin-4-yl)oxy) acetylamino alkanoate have been developed via N,N 0dicyclohexylcarbodiimide coupling of (2-arylquinazolin-4-yloxy) acetic acids with amino acid ester hydrochlorides. The O-substituted carboxylic acids were prepared by two-step reactions from the corresponding 2arylquinazolin-4(3H)-one starting with chemoselective O-alkylation with ethyl chloroacetate and then hydrolysis of the produced esters. The reason for this O-chemoselective behavior of 2-arylquinazolin-4(3H)one toward electrophiles was explained by theoretical density functional theory computational calculations on the model compound 2-phenylquinazolin-4(3H)-one. The antimicrobial activity of the synthesized compounds was evaluated, showing the best inhibition zone for (2-arylquinazolin-4-yloxy) acetic acids, methyl 2-(2-(2-arylquinazolin-4-yl)oxy) acetylamino acetates, and methyl 2-(2-(2-phenylquinazolin-4-yl)oxy) acetylamino-3-methylbutanoate.Scheme 2. Synthesis of methyl 2-(2-(2-arylquinazolin-4-yl)oxy) acetylamino alkanoates 7-8(a-f).

No abstract

A highly efficient and versatile synthetic approach for the synthesis of 4-(pyren-1-ylmethyl)-1-(d-glycosyloxy) phthalazine nucleosides 11a,b, 13, β-S-nucleosides 16, 18, 20, and acyclo C-nucleosides 23a,b, 24, 25 and 27a–f was described and fully characterized. Furthermore, a series of desired new nucleoside analogues containing Se of 4-(pyren-1-ylmethyl) phthalazine-1(2H)-selenone 28–33 were synthesized. The structures of all reported compounds were confirmed by IR, 1H-NMR, 13C-NMR, MS and elemental analysis. All compounds have been screened for their antibacterial and antifungal activities. Maximum activity was shown by 20 and 33a comparable to the standard drugs with lower toxicity. The cytotoxicity of the selected compound was measured and evaluated. The energy gap between the highest occupied molecular orbital and lowest unoccupied molecular orbital was calculated using theoretical computations to reflect the chemical reactivity and kinetic stability of the synthesized compounds. Using density functional theory (DFT), electronic parameters such as the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) and the molecular electrostatic potential (MEPS) were calculated. On the basis of different studied structures, these properties were computed in order to elucidate the chemical reactivity and the kinetic stability. Obviously, the band gap energy (Eg) of structures studied reveals that the lowest band gap obtained for the structure 16-a indicates that it has the highest chemical reactivity and lowest kinetic stability.

A series of methyl [3-alkyl-2-(2,4-dioxo-3,4-dihydro-2H-quinazolin-1-yl)-acetamido] alkanoate 10-13a-f has been developed on the basis of the N-chemoselective reaction of 3-substituted quinazoline-2,4-diones 3a-d with ethyl chloroacetate and azide coupling method with amino acid ester hydrochloride. The precursor quinazoline diones 3a-d chemoselective reactions were studied using DFT(B3LYP)/6-311G level of theory and were prepared by a new rearrangement method from the corresponding 2-(3-methyl-4-oxo-3,4-dihydroquinazolin-2-ylthio) acetohydrazide 6.