الفهرس 
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Abstract
In continuation of our efforts to develop the synthesis and reactivity of benzoxazinone derivatives toward some nitrogen and oxygen nucleophilic reagents we reported here, the synthesis of novel 6-iodo-2-(4-nitrophenyl) benzo[d][1,3]oxazine-4-one (2) via condensation of 4-nitrobenzoyl chloride with 5- iodoanthranilic acid in pyridine via the intermediacy of benzoic acid derivative 1 (scheme1).
Reaction of 6-iodo-2-(4-nitrophenyl)benzo[d](1,3)oxazine-4-one (2) with nucleophiles considering the special structure of 6-iodo-4H-3,1-benzoxazin-4-one derivatives, there are two sites available for nucleophilic attack (position-2 and -4), i.e. two different sites with partial positive charge that can lead to the opening of oxazinone nucleus by different attacking nucleophiles. In most cases, reclosure of the heterocyclic part of the molecule is favored and provides a new compound with interesting chemical and biological properties. Competition between the two mentioned sites toward nucleophilic attack depends on different parameters such as the size, the nucleophilicity, and the nature of the nucleophile with respect to the two rings of 6-iodo-4H-3,1-benzoxazin-4-one as well as on the reaction conditions. Also steric factors play an important role on the reaction pathway. In other words, the electron density and the size of the substituent at position-2 will control the reaction pathway. The reaction of oxazine 2 with aniline, hydrazine hydrate and phenyl hydrazine in boiling ethanol gave 6-iodo-2-(4-nitrophenyl)-3-phenylquinazolin-4(3H)-one (3), 3-amino-6-iodo-2-(4-nitrophenyl) quinazolin4(3H)-one (4), 6-iodo-2-(4-nitrophenyl)-3-(phenylamino)quinazolin-4(3H)-one (5) respectively. (scheme.2)
Recently it is reported that the behavior of 2-substituted-4H-3, 1 -benzoxazin-4-one derivatives toward ammonia and/or formamide with the aim of converting benzoxazinone derivatives into the more stable quinazolinone derivatives. Similarly, when oxazine 2 was allowed to react with ammonium acetate in oil bath at 150°C yielded 6-iodo-2-(4-nitrophenyl)quinazolin-4(3H)-one (6).The reaction of oxazine 2 with glycine gave 2-(6-iodo-2-(4-nitrophenyl)-4-oxoquinazolin-3(4H)-yl)acetic acid (7) (scheme 2)
Reactions of 6-iodo-2-(4-nitrophenyl)quinazolin-4(3H)-one (6) with phosphorus oxychloride and/or phosphorus pentachloride yielded the chloroquinazoline 8 which reacts with nucleophiles as hydrazine hydrate in boiling ethanol and gave 4-hydrazinyl-6-iodo-2-(4-nitrophenyl)quinazolin (9). Reaction of the quinazoline 6 with ethyl chloroacetate in dry acetone afforded Ethyl 2-[(6-iodo-2-(4-nitrophenyl)quinazolin-4-yl)oxy ]acetate (10). Behavior of quinazoline 10 towards hydrazine hydrate in boiling ethanol was also investigated to give 2-[(6-iodo-2-(4-nitrophenyl)quinazolin-4-yl)oxy]acetohydrazide (11) (scheme 3).
The reaction of quinazoline derivative 7 with thionyl chloride followed with ammonium thiocynate gave isothiocyanate 13. The behavior of isothiocyanate 13 towards some nucleophiles and some active methylene compounds under Michael reaction condition was also investigated. (Scheme 4).
As extension of this synthetic route for the synthesis of biologically active heterocyclic systems, the present investigation also, focused on the synthesis of triazole 22 derivatives, which are used as key precursor for the synthesis of antimicrobial heterocycles. (scheme 5).
Biological activity of some synthesized compounds which have been investigated in antimicrobial screening suggests that all the newly synthesized compounds showed moderate to good activity against the tested organisms, also extraction of some newly heterocyclic organic compounds as Humic and Fulvic acid beside quinazolines to improve soil through the removal of some heavy metals from soil.
Structure of all synthesized derivatives was established by:
1- Elemental analysis
2- I.R spectra
3- 1H NMR
4- Mass spectra