Fused Heterocyclic Nitrogen Systems Containing Phosphorus Atom

Synthesis of fused heterocyclic nitrogen systems containing phosphorus atom via (1+4) Cyclocondensation, (3+2) cycloaddition, and 1,5-electrocyclization reactions are reviewed. Also, the modified synthesis methodology applicable to the fused phospha-five and six-membered rings.


INTRODUCTION
Organophosphorus compounds Research has steadily flourished 1 because these compounds have been reported to possess anti-TMV activity 2 , herbicides 3,4 , insecticides 5,6 , molluscidal 7 , and some of here useful as strong basic proazaphosphatrans 8 , complexes 9,10 also as superior catalyst of the protective silyation of wide variety of sterically hindered and deactivated alcohols 11 .
Fused and isolated heterocyclic nitrogen systems have been testified as anticancer 12,13 and plant protection 14 activities.In addition, phosphorus containing heterocyclic compounds exposed interesting biologically active 15,16 .Thus, in the present review an attempt has been made to
A related condensation of 1-alkyl-2aminopyridinium salt (11) with PCl 3 in presence of Et 3 N led to the formation of 1-aza-2phosphindolizines (13) via the intermediate 12.

+
The pesticides are a group of chemicals intended for perveting/destroying production, processing storage transportation and distribution of food.Thus, thiophosphate pesticides are the most effective insecticides and are used to control a wide variety of insect's pest as Parathion 6 (41).Also the insecticide as Dimethaoate 5 (42).

49
On the other hand, 3-amino-6-methyl-5styryl-1,2,4-triazine (50) react with CS 2 in alcoholic KOH to give (6-methyl-5-styryl-1,2,4-triazin-3yl)dithiocarbamic acid (51), which work as a building block for fused phospha-heterobicyclic systems 52-57 as bi-six-membered rings 22  The behavior of marcapto group in compound 51 towards halogenated phosphorus reagents to produce compounds 55-57 is similar to its reaction with various alkylating agents and or ketonic agents.It is worthy of mention that nucleophilic attack on SH is more than NH group by chlorinated phosphorus reagents 48  The tautomeric structures and proton mobility in position 3 and 2 of 1,2,4-triazines considered to be important in heterocyclization process with halogenated phosphorus reagents. 22lso, the reactivity structure relationship showed that phospha-1,2,4-triazine similar as Atranes which have unexpected properties 49 .
Ibrahim et al 50  was isolated under refluxing [Scheme 18] 6 .Due to driving force of P=O bond is strong and phenyl groups are bad leaving groups, the nucleophilic attack of hydrazine moiety may be carried out at carbonyl group then P=O group 6 .Phosphorus compounds with a ±-nitrogen or ±-oxygen more often exhibited interesting biological properties 56 .Thus, introducing of P-C-O or P-C-N pattern into heterocyclic systems may be enhancing their biocidal effects.Thus, compounds 62-71 showed strong effects on the tested snails, which due to facile donation and back donation in d-orbital of phosphorus atom 6 .
Condensation of 4-oxo-4H-chromene-3carboxaldehyde (72) with phosphonic dihydrazide In 13 CNMR spectra these compounds absorb further downfield in the range  265-218.Also, N-isoquinolinium 79 reacts with R-CºP in boiling toluene (glass pressure tube) 61  Most spectral study of organophosphorus heterocyclic compounds has been undertaken because of their wide applications in agriculture as pesticide and industry, The mass spectra of a series of 2-substituted-2,3-dihydro-1H-naphtho[1,8de](1,3,2)-diazaphosphorine-2-oxides (88) were studied to establish their fragmentation processes.The major fragmentation patterns are the loss of aryloxy substituent and RPO 2 H moieties from the molecular ion.The fragmentation pattern is supported by meta stables, high resolution and collision activation dissociation data [Scheme 20A] 61a .Raju et al 61 b , reported the synthesis, electron impact and high resolution mass spectral of 2substituted-3-( 4

Spectrophotometric Determinations of Phosphorus
Numbers of spectrophotometric methods for determination of phosphorus, based on the formation of heteropoly acid with molybdate have been described.The molar absorptivity of these heteropoly acids in the aqueous solution or in organic solvents after solvent extraction, are generally low 61 .Several cationic dyes, for example; methylene blue, ethyl violet, crystal violet, auramine, malachite green have been used for the determination of phosphorus 62 .The spectrophotometric determination of phosphates using above dyes processes have limited use due to several disadvantages. 63cently, A novel curing agent of epoxy resins (EPO), bis(3-amino-2-thienyl) phenylphosphine oxide (ABTPPO), was synthesized and characterized.ABTPPO was used as a flame retardant curing agent, and used to prepare a novel halogen-free flame retardant EPO composite. 64In addition to a reported of a miniature flow-through detector methods useful for bimodal, photometric and fluorimetric, determination of phosphates 65 and A simple manifold flow injection analysis (FIA) for determining phosphorus in the presence of arsenate in water 66
The developments in this area will help to persuade the important strategy to synthesis of phospha-heterocyclic nitrogen-five and sixmembered rings.

Scheme 13 :
Scheme 13: Synthesis of some marcapto group compound
Scheme 20: Mass fragmentation of compound 88