Spectroscopic Investigations and DFT Calculations on 3-(Diacetylamino)-2-ethyl-3H-quinazolin-4-one

Yusuf Sert,Amany S Hegazy,Fatih Ucun,Gamal A El-Hiti,Keith Smith

doi:10.1155/2016/5396439

Abstract

The theoretical and experimental vibrational frequencies of 3-(diacetylamino)-2-ethyl-3H-quinazolin-4-one (2) were investigated. The experimental Laser-Raman spectrum (4000–100 cm−1) and FT-IR spectrum (4000–400 cm−1) of the newly synthesized compound were recorded in the solid phase. Both the theoretical vibrational frequencies and the optimized geometric parameters such as bond lengths and bond angles have for the first time been calculated using density functional theory (DFT/B3LYP and DFT/M06-2X) quantum chemical methods with the 6-311++G(d,p) basis set using Gaussian 03 software. The vibrational frequencies were assigned with the help of potential energy distribution (PED) analysis using VEDA 4 software. The calculated vibrational frequencies and the optimized geometric parameters were found to be in good agreement with the corresponding reported experimental data. Also, the energies of the lowest unoccupied molecular orbital (LUMO), highest occupied molecular orbital (HOMO), and other related molecular energies for 3-(diacetylamino)-2-ethyl-3H-quinazolin-4-one (2) have been investigated using the same computational methods.

Highlights

Quinazoline derivatives are of interest because they show a variety of biological activities including anti-inflammation [1], antibacterial [2], antispasm [3], anticancer [4, 5], antiobesity [6] and reductase inhibitory properties [7]
Quinazolin4-one derivatives have been synthesized by various methods, for example, reactions of carbon dioxide with 2aminobenzonitrile without use of a catalyst in water [8]; reactions of N-substituted 2-bromobenzamides with formamide catalysed by CuI and 4-hydroxy-l-proline [9]; threecomponent reactions of benzyl halides, isatoic anhydride, and primary amines under mild Kornblum conditions [10]
We have shown that the quinazoline ring system can be modified via lithiation by a lithium reagent such as alkyllithium in anhydrous tetrahydrofuran at low temperature followed by reactions with electrophiles to provide access to substituted derivatives in high yields

Summary

Introduction

Quinazoline derivatives are of interest because they show a variety of biological activities including anti-inflammation [1], antibacterial [2], antispasm [3], anticancer [4, 5], antiobesity [6] and reductase inhibitory properties [7]. We have shown that the quinazoline ring system can be modified via lithiation by a lithium reagent such as alkyllithium in anhydrous tetrahydrofuran at low temperature followed by reactions with electrophiles to provide access to substituted derivatives in high yields. Such derivatives might be difficult to synthesize by other means [11,12,13,14,15]. As far as we are aware, there have been no previous reports of quantum chemical calculations or FT-IR and Laser-Raman spectral studies on 3-(diacetylamino)-2-ethyl3H-quinazolin-4-one (2). We report experimental infrared and Raman spectra along with quantum chemical calculations, which correlate well with each other, to enable vibrational frequencies for compound 2 to be assigned

Experimental Details

Computational Details

Results and Discussion

Conclusion