Fused Heterocyclic Nitrogen Systems Containing Phosphorus Atom

Introduction

Organophosphorus compounds Research has steadily flourished[1] because these compounds have been reported to possess  anti-TMV activity², herbicides^3,4, insecticides^5,6, molluscidal⁷, and some of here useful as strong basic proazaphosphatrans⁸, complexes^9,10 also as superior catalyst of the protective silyation of wide variety of sterically hindered and deactivated alcohols¹¹.

Fused and isolated heterocyclic nitrogen systems have been testified as anticancer^12,13 and plant protection¹⁴ activities. In addition, phosphorus containing heterocyclic compounds exposed interesting biologically active^{15, 16}. Thus, in the present review an attempt has been made to highlight the synthesis and properties of fused heterocyclic systems containing phosphorus atom.

Distribution

The Synthetic strategy for new organophosphorus heterocyclic systems was analogous to the Krohnke`s synthesis¹⁷ via [4+1] cyclo condensation, [3+2] cycloaddition¹⁸ and 1,5-electrocyclization¹⁹. Bansal et al^20,21 and abdel-Rahman²² reported a brief reviews about the synthesis of indolizines and phosphaindolizines.

Synthesis via [4+1] cyclocondensation reactions are most important. Thus, synthesis of 2-phosphoindolizines (3) was deduced from condensation of 1,2-dialkylpyridinium bromide (1) with PCl₃ in presence of Et₃N via intermediate 2 [Scheme 1]^{23, 24}.

 

Scheme1: synthesis of 2-phosphoindolizines  Click here to View scheme

 

If R² is methyl group, that reaction proceeds through the intermediate 5 to yield 1-dichlorophosphino-2-phosphoindolizine (6) [Scheme 2]²⁵.

Scheme2: synthesis of 1-dichlorophosphino-2-phosphoindolizine  Click here to View Scheme

 

Similarly, 1,3-azaphospholo[5,1-b]thiazolines (7) and 1,3-azaphos-pholo[5,1-b]benzothiazoles (8) were synthetic²⁶.

On the other hand, 1-phosphaindolizines (10) was obtained from condensation of 1,3-oxazolo[3,2-a]pyridinium salt (9) with P(SiMe₃)₃ via exchange oxygen by phosphorus²⁷.

Scheme 2A  Click here to View scheme

 

A related condensation of 1-alkyl-2-aminopyridinium salt (11) with PCl₃ in presence of Et₃N led to the formation of 1-aza-2-phosphindolizines (13) via the intermediate 12. [Scheme 3]²⁸.

Scheme 3  Click here to View scheme

 

A large number of 3-aza-2-phosphaindolizines (15) were prepared²⁹ from condensation of 2-alkyl-1-aminopyridinium iodides (14) with PCl₃ in presence of Et₃N.

Scheme 3A  Click here to View scheme

 

Also, 3-aza-phosphaindolizines (17) have been synthetic via O/P exchange of 1,3,4-oxadiazolo[3,2-a]pyridinium salts (16) with P(SiMe₃)₃³⁰.

Scheme 3B  Click here to View scheme

 

It is interesting that phospha-fused heterobicyclic as 1,3-diaza-2-phosphaindolizines (19) were obtained from cyclocondensation of 1,2-diaminopyridinium iodides (18) with P(NMe₃)₃ in boiling dry benzene³¹.

Scheme 3C  Click here to View scheme

 

Karaghiosoff et al³² reported the using of chloromethyl dichloro-phosphine (ClCH₂PCl₂) as equivalent reagent yielding two-heterocyclic fused via C – P moiety by cyclocondensation with 2-substituted azoles and azines through [3+2]cyclocondensation reactions³³.

Thus, 2-aminopyridine (20) condenses with (ClCH₂PCl₂) in presence of Et₃N to produce 1,4,2-diazaphospholo[4,5-a]pyridine (21)³⁴.

Scheme 3D  Click here to View scheme

 

On the other hand, [3+2] cycloaddition reactions were used tert-butylphospha acetylene 1,3-dipolarophile to condense with pyridinium (22) to give 2-phosphaindolizine (23) by boiling in dry toluene¹⁸.

Scheme 3E Click here to View scheme

 

Azomethine ylides and azomethine imines incorporate that structure of 1,3-dipolar moiety bonded directly to an olefinic or acetylenic bond possesses 1,5-dipolar structure and have been utilized for the synthesis of five-membered heterocycles^{19, 35}

Thus, disproportionation of N-pyridinium dichlorophosphonium-methylides (24) would generate the bis-(N-pyridiniumylidyl) phosphonium chloride (25) which on disproportionation via 1,5-electrocyclization by loss the pyridinium hydrochloride to yield 2-phosphaindolizine (26) [Scheme 4]³⁶.

Scheme4: Synthesis of 2-phosphaindolizine  Click here to View scheme

 

Abdel-Rahman²², reported the synthesis of new phosphaheterobi-cyclic system containing 1,2,4-triazine moiety via heterocyclizationa, this in cloud a novel synthesis of fluorine bearing 5-phospha-1,2,4-triazin-3-thiones and 5-phospha-1,2,4-triazepin-3-thione.

Thus, a facile synthesis of fused phosphaheterobi-cyclic nitrogen system containing 1,2,4-triazine moiety was describe earlier. The treatment N-substituted thiosemicarbazides³⁷ (27) with diethyl benzoyl phosphate and/or diphenyl(2,4,6-trimethyl benzoyl) phosphine oxide in boiling dry toluene or THF³⁸ afforded 4,5,6-trisubstitued-5-phospha-1,2,4-triazin-3(2H)thiones (28 & 29) respectively. Refluxing both the compounds 28 and 29 with trifluoroacetic anhydride yielded³⁹ the full fluorinated phospha-1,2,4-triazinethiones 30 and 31 respectively [Scheme 5]²².

Scheme5: synthesis of fused phosphaheterobi-cyclic nitrogen system containing 1,2,4-triazine moiety    Click here to View scheme

 

correspondingly, cyclocondensation of N 4-substituted thiosemicarbazide (27) with acetonyltriphenylphosphonium chloride in boiling THF-DMF⁴⁰ led to the direct formation of hexahydro-4,7-disubstituted-5-triphenyl-5-phospha-1,2,4-triazepin-3-(2H)thione (32)²².

Presence of  both NH and CH₂ groups in the compound 32 was deduced from acylation and or condensation with trifluorobenzaldehyde⁴⁰ to give the final products fluorine-bearing 1,2,4-triazepin-3-thione derivative (34) [Scheme 6]²².

Scheme6: Synthesis of fluorine-bearing 1,2,4-triazepin-3-thione derivative  Click here to View scheme

 

Regioselective iminophosphoran-mediated annelation of a 1,3,4-thiadiazole ring into a 1,2,4-triazine ring was studied by Molina et al⁴². These studies based on aza-Wittig type reaction of iminophosphoane (37) followed by addition isothiocyanate-formed mesomeric or Zwitter ionic character 35 and 36. Treatment of compound 36 with primary aromatic amines afforded the Betaine 37 which under treatment with ethanol in the presence of tetrafluoro boric acid by stirring for 7 hours, resulted the 1,3-thiadiazetidines 38 via carbodiimide under goes [2+2] cycloaddition reaction [Scheme 7]⁴².

Scheme7: Synthesis of 1,3-thiadiazetidines  Click here to View scheme

 

From survey and various publications, it showed that a lethal work on the area of phospha-1,2,4-triazines^41-43. The first study between phosphorus and 5,6-diphenyl-1,2,4-triazin-3(2H) one (39) and some phosphorus reagents such as TPP, P(OR)₃ and (CH₂)₂O₂PZ (Z = Cl, OMe, N(Me)₂) were isolated phospha-heterocyclic system 40 obtained⁴³.

Scheme 7A  Click here to View scheme

 

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 Parathion⁶ (41). Also the insecticide as Dimethaoate⁵ (42).

Scheme 7B  Click here to View scheme

 

Several studies ^12,13,44 found that fused heterobicyclic nitrogen systems have a wide spectrum of medicinal and biological activities. Thus, treatment²² of 3-amino-5,6-dimethyl-1,2,4-triazine (43) with triphenylphosphine dibromide in toluene³⁸ afforded compound 44, while refluxing of 43 with (EtO)₃P=O in dry toluene⁴⁵ yielded compound 45 [Scheme 8]²².

Scheme8: Synthesis of fused heterobicyclic nitrogen systems  Click here to View scheme

 

In addition, condensation of 3-amino-triazine 43 with aromatic aldehyde and (p-ClC₆H₄)₃P and/or acetophenone/ArPCl₂ in presence of dry toluene^40,46-TEA led to the direct formation of phospha heterocyclic systems 46 and 47 respectively [Scheme 9]²³. Formation of compound 46 may be takes place as shown in Scheme 10⁴⁷.

Scheme9: Condensation of 3-amino-triazine 43 with aromatic aldehyde  Click here to View scheme

 

Scheme10: Formation of compound 46  Click here to View scheme

 

In addition, the reaction of 3-amino-5,6-dimethyl-1,2,4-triazine (43) with diethyl benzyl phosphonate and/or (NEt₂)₃P⁺ Br^– in dry toluene produced the phospha heterocyclic systems 48 and 49 respectively [Scheme 11]²³.

Scheme11: Phospha heterocyclic systems  Click here to View scheme

 

On the other hand, 3-amino-6-methyl-5-styryl-1,2,4-triazine (50) react with CS₂ in alcoholic KOH to give (6-methyl-5-styryl-1,2,4-triazin-3-yl)dithiocarbamic acid (51), which work as a building block for fused phospha-heterobicyclic systems 52-57 as bi-six-membered rings²². Thus, compound 51 on treatment with phosphorus reagents such as (Ph)₃PBr₂, P(NR₂)₃ and (MeO)₃P=O in refluxing toluene-TEA furnished 1,2,4-triazino[2,3-c][1,2,5,2]thiadiapho-sphorin-6-thiones (52-54) respectively [Scheme 12]²².

Scheme12: Synthesis of 1,2,4-triazino[2,3-c][1,2,5,2]thiadiapho-sphorin-6-thiones   Click here to View scheme

 

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 reagents⁴⁸. Thus, refluxing compound 51 with CNCH₂P(O)(OEt)₂, PhCH₂P(O)(OEt)₂ and Br^– P⁺(NEt₂)₃ in THF-DMF furnished the target compounds 55-57 [Scheme 13]²².

Scheme13: Synthesis of some marcapto group compound  Click here to View scheme

 

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. ²² Also, the reactivity structure relationship showed that phospha-1,2,4→triazine similar as Atranes which have unexpected properties⁴⁹.

Ibrahim et al⁵⁰, reported the synthesis of novel 1,2-thiaphos-pholo[4,5- e][1,2,4]triazines (60) by treatment of 1,2,4-triazin-6-one (58) and or 1,2,4-triazin-6-thione (59) with different percentage of Lawesson`s reagent (LR)⁵¹ [Scheme 14].

Scheme14: synthesis of novel 1,2-thiaphos-pholo[4,5- e][1,2,4]triazines  Click here to View scheme

 

The molecular modifications of 1,2,4-triazine rings by introducing organophosphorus functionalities might be expected to exhibit the potential activities depending on the position of the phosphoryl group to 1,2,4-triazine ring, Abdel-Rahman et al⁶, studied synthesis of phosphorus containing fused and isolated heterobicyclic nitrogen systems via reaction of 5,6-bis(4-bromophenyl)-3-hydrazino-1,2,4-triazine (61) with some phosphorus reagents in non-polar solvent under various temperatures, the 6,7-diaryl-2,3-dihydro-3,3,3-triphenyl-1,2,4,-triazaphospholino[4,5-b][1,2,4]triazine (62) was synthesized by stirring compound 61 with dibromotriphenylphosphorane in THF at room temperature for 24 hours [Scheme 15]⁶. Formation of 62 may be occurred via heterocyclization of the intermediate N¹,N²-disubstituted hydrazine. The ¹³CNMR spectrum of compound 62 showed signal at δ 29.61 ppm⁵².

Scheme15: Synthesis of 6,7-diaryl-2,3-dihydro-3,3,3-triphenyl-1,2,4,-triazaphospholino[4,5-b][1,2,4]triazine  Click here to View scheme

 

Phosphorylation of 3-hydrazino-1,2,4-triazine 61 via treatment with acetonyl triphenylphosphonium chloride under stirring in THF-piperidine for 24h, at room temperature furnished N¹,N²-disubstituted hydrazine 63. Ring closure of 63 by heating above its melting point produced the heterobicyclic system 64 [Scheme 16]⁶. On the other hand, that reaction when carried out under refluxing, the isomeric structure 5,6-bis-aryl-3-{(3,3,3-triphenyl)-5-methyl-3,4-dihydro-2H-1,2,3-N⁵–diazaphosphol-2-yl}-1,2,4-triazine (65) [Scheme 16]⁶.

Scheme16: Synthesis of some heterocyclic system  Click here to View scheme

 

the treatment of 3-hydrazinotriazine 61 with diethylphosphite and/or 2-chlorophenyl di-chlorothiophosphate in THF/piperidine at room temperature produced the phosphonohydrazide 66 and phosphono-hydrzidothionic acid 67 respectively [Scheme 17], while the reactions under reflux afforded directly the 1,2,4,3-triazaphospholo[4,5-b][1,2,4]triazines 68 and 69 respectively [Scheme 17]. ¹HNMR spectra of 68 and 69 showed signals of NH protons at δ10.92 and 10.34 ppm, respectively with respect to similar reported data^53-55.

imilarly, compound 70 isolated from treatment of 61 with diphenyl(2,4,6-trimethylbenzoyl)phosphorus oxide by stirring with THF at room temperature while 7,8-bisaryl-4,4-diphenyl-3-(2`,4`,6`-trimethyl-phenyl)-4H-4⁵1,2,4-triazino[3,2-c][1,2,4,5]triaza- phosphinin-4-ol (71) 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 group⁶.

Scheme17:Synthesis of  1,2,4,3-triazaphospholo[4,5-b][1,2,4]triazines 68 and 69  Click here to View scheme

 

Scheme18: Synthesis of compound 71  Click here to View scheme

 

Phosphorus compounds with a α-nitrogen or α-oxygen more often exhibited interesting biological properties⁵⁶. 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 atom⁶.

Condensation of 4-oxo-4H-chromene-3-carboxaldehyde (72) with phosphonic dihydrazide (1:1 by moles) when heated in boiling ethanol yielded the mono-hydrazone 73. Addition of diethyl phosphite to the azomethine bond of monohydrazone 73 by heating at 80-100ºC in TEA led to the direct formation of 3-(4-amino-5-ethoxy-3,5-dioxido-1,2,4,3,5-triazadiphosphinan-6-yl)4H-chromen-4one(74) [Scheme 19]^{57, 58}.

Scheme19: Synthesis of 74  Click here to View scheme

 

Pnickuk et al⁵⁹, reported that the intramolecular heterocyclization of polysubstituted pyrazole 75 afforded the fused phospha-heterobicyclic systems 76 via loss of dialkylamine.

Scheme 19A  Click here to View scheme

 

Functionally 1,2,4,3-triazaphospholopyridines (78) were obtained from [1+4] cycloaddition of 1-amino-2-imino-2H-pyridine-3-carbonitrile (77) with P(NMe₂)₃ in refluxing benzene⁶⁰.

Scheme 19B  Click here to View scheme

 

In ¹³CNMR spectra these compounds absorb further downfield in the range δ 265-218.

Also, N-isoquinolinium 79 reacts with R-CºP in boiling toluene (glass pressure tube)⁶¹ to form the 1,3-azaphospholoquinoline derivatives 80

Scheme 19C Click here to View scheme

 

Under the same conditions, [3+2] cycloaddition of N-cycloimmoni-um ylide 81 with phosphaalkyne (82) has been successfully employed to synthetic of 1,3,4-azaphospholo[1,2-a]Phthalazine (83)⁶¹.

Scheme 19D Click here to View scheme

 

On the other hand, 2,3-dialkylbenzothiazolium bromides (84) when condense with PCl₃/ Et₃N led to the direct formation of compound 85⁶² .

Scheme 19E  Click here to View scheme

 

In addition, 3-alkyl-2-aminobenzthiazolium (86) when react with PCl₃/ Et₃N yielded the 1,2,4-phosphazabenzthiazole 87^63,64.

Scheme 19F  Click here to View scheme

 

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[1,8-de](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 RPO₂H 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  2-substituted-3-(4-methylphenyl)-naphth[1,2-e](1,3,2)oxazaphosphorine-2-oxides/sulfide.

Scheme20: Mass fragmentation of compound 88  Click here to View scheme

 

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 low⁶¹. Several cationic dyes, for example; methylene blue, ethyl violet, crystal violet, auramine, malachite green have been used for the determination of phosphorus⁶². The spectrophotometric determination of phosphates using above dyes processes have limited use due to several disadvantages.⁶³

Recently, 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.⁶⁴ In 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 water⁶⁶

Conclusion

This review cover published literature concerning the synthetic of fused biheterocyclic nitrogen containing phosphorus atom over the period 1999-2014, updating our earlier review⁶ and on the area of bioactive 1,2,4-triazine derivatives^{11,12,40,67,68, 69}.

The developments in this area will help to persuade the important strategy to synthesis of phospha-heterocyclic nitrogen-five and six-membered rings.

References

1. M. Balali-Mood, M. Abdollahi (eds.), Basic and Clinical Toxicology of Organophosphorus Compounds, DOI 10.1007/978-1-4471-5625-3, Springer-Verlag London 2014, p 25-34.
2. Q. Dai, R. Chen; Phosphorus, Sulfur and Silicon 1997, 122, 261.
3. L. Nion, F. C. Ru-Yn Chen, J. A. Zhou, Phosphorus, Sulfur and Silicon 1997, 130, 65.
4. J. S. Tang, J. G. Verkade; U S Patent, 5 260 436 1993; Chem. Abstr. 1993, 120, 218836v.
5. A. K. Tiwari, B. K. Dubey, I. C. Shukla, J. Indian Chem. Soc. 2003, 80, 717.
6. I. C. Shukla, P. K. Dwived, J. Indian Chem. Soc. 2005, 82, 670.
7.  T. E. Ali, R. M. Abdel-Rahman, F. I. Hanafy; Phosphorus, Sulfur and Silicon 2008, 183, 1-13.
8. A. E. Wroblewski, J. Pinkas, J. G. Verkade, Main Group Chem. 1995, 1, 69.
9. A. Naiini, V. G. Young, J. G. Verkade; Polyhedron, 1997, 16, 2087.
10. P. Mc Laughlin, J. G. Verkade; Organometallics, 1998, 17, 5937.
11. B. D. Sa, J. G. Verkade; J. Am. Chem. Soc., 1996, 118(12), 832.
12. R. M. Abdel-Rahman; Pharmazie, 2001, 56(1), 18-22.
13. R. M. Abdel-Rahman; Pharmazie, 2001, 56(3), 195-204.
14. R. M. Abdel-Rahman; Boll. Chim. Farmaceutico, 2001, 140,401.
15. Y. Xu, K. Yan, B. Song, G. Xu, S. Yang, W. Xue, D. Hu, P. Lu, L. Ouyang, Z. Chen; Molecule, 2006, 11, 6660.
16. L. Wan, I. Alkorta, J. Elguero, J. Sun, W. Zheng; Tetrahedron, 2007, 63, 9129.
17. F. W. Krock, F. Krohnke; Chem. Ber., 1969, 102, 659.
18. U. Bergstra, A. Hoffmann, M. Regitz; Tetrahedron Lett. 1992, 33, 1049.
19. R. H. Huisgen, J. Org. Chem., 1976, 41, 403.
20. R. K. Bansal, K. Karaghosoff, N. Gupta, A. Schmidpeter, C. Spindler, Chem. Br., 1991, 124, 475.
21. R. K. Bansal, N. Gupta, A. Surana; J. Indian Chem. Soc., 1998, 75, 648.
22. R. M. Abdel-Rahman; Trends Heterocycl. Chem., 2002, 8, 187.
23. R. K. Bansal, V. Kabra, N. Gupta, K. Karaghiosoff; J. Indian Chem. Soc., 1992, 31B, 254.
24. N. Gupta, C. B. Jain, J. Heinnicke, N. Bharatiya, R. K. Bansal, P. G. Jones; Heteroatom Chem., 1998, 9, 333.
25. R. K. Bansal, N. Gupta, R. Gupta, G. Pandey, M. Agarwal; Phosphorus, Sulfur and Silicon 1996, 112, 121.
26. R. K. Bansal, R. Mahnot, D. C. Sharma, K. Karaghiosoff, A. Schmidpeter; Heteroatom Chem., 1992, 3, 351.
27. G. Markl, S. Pflaum; Tetrahedron Lett. 1987, 28, 1511.
28. K. Karaghiosoff, R. K. Bansl, N. Gupta; Z. Naturfosch. Teil B. 1992, 47, 373.
29. R. K. Bansal, G. Pandey, R. Gupta, K.  Karaghiosoff, A. Schmidpeter; Synthesis, 1995¸173.
30. G. Markl, S. Pelaum, Tetrahedron Lett., 1988, 29, 3387.
31. R. K. Bansal, N. Gandhi, K. Karaghiosoff, A. Schmidpeter; Z. Naturforsch. Teil, 1995, 50, 558.
32. K. Karaghiosoff, A. Schmidpeter, P. Mayer “Synthetic Methods in Organometallic Chemistry”. G. Thieme, Stuttgart, 3, Group, 1995.
33. K. Karaghiosoff, C. Cleve, A. Schmidpeter; Phosphorus, Sulfur, 1986, 28, 289.
34. I. A. Litvinov, K. Karaghiosoff, A. Schmidpeter, E. Y. Zabotina, E. N. Dianora; Heteroatom Chem., 1991, 2, 369.
35. E. C. Taylor, I. J. Turchi; Chem. Rev., 1979, 79, 2.
36. A. Schmidpeter, G. Jochem; Tetrahedron Lett., 1992, 33, 471.
37. P. Molina, M. Alajarin, A. Lopez-Lazaro; J. Chem. Soc., Perk. Trans. 1986, 1(12), 2037 .
38. P. Molina, M. Alajarin, A. Lopez-Lazaro; Tetrahedron, 1990, 46(12), 4353.
39. Q. Dai, R. Chen; Phosphorus, Sulfur and Silicon 1997, 122, 261.
40. J. Zhou, Y.Qui, K. Feng, R-Y. Chen; Synthetic Commn., 1998, 28(24), 4673.
41. R. M. Abdel-Rahman; Phosphorus, Sulfur and Silicon 2000, 166, 315.
42. P. Molina, M. Alajarin, A. Lopez-Lazaro; Tetrahedron, 1991, 47(33), 6747.
43. Y. O. El-Khoshnieh; Phosphorus, Sulfur and Silicon 2000, 139, 163.
44. Y. O. El-Khoshnieh, Y. A. Ibrahim; Phosphorus,  1995, 101, 67.
45. Z. El-Gendy, J. Morsy, H. Allimony, W. Abdel-Momen, R. M. Abdel-Rahman Phosphorus, Sulfur and Silicon 2003, 178(9), 2055.
46. R. Lu, N. Yang, Z. Shang, Phosphorus, Sulfur and Silicon 1996, 108, 197.
47. M. R. Mohan, T. S. Hafez, M. M. Henary; Phosphorus, Sulfur and Silicon 1998, 139, 13 .
48. T. B. Hwang, L. Feiliu, W.-Qian Yan, X.-Ming Yu, Xu.-Hong Qian, J.-L. Zkang; Phosphorus, Sulfur and Silicon 1997, 122, 299.
49. S. N. Tandura, M. G. Voronkov, N. V. Alekseer; Top. Curr. Chem., 1986, 131, 99.
50. M. A. H. Laramary, J. G. Verkade, Z. Anorg; Allg. Chem., 1991, 605, 163.
51. Y. A. Ibrahim, A. M. Kadry, M. R. Ibrahim, J. N. Lisgarten, B. S. Potfer, R. A. Palmer; Tetrahedron 1999, 55, 13457.
52. L. Nian He, R.-XI, Zhuo, X-Peng Liu, F. Caio, Phosphorus, Sulfur and Silicon 1999, 144, 453.
53. Y. Haribaba, M. A. Kumar, K. Srinivasulu, C. S. Reddy, C. N. Raju; Arkivoc, 2006, 189.
54. M. Maffei, G. Buono, Tetrahedron 2003, 59, 8821.
55. M. R. Bryce, R. S. Matthews; J. Organomet. Chem., 1997, 325, 153.
56. J. Hernadez, F. M. Gaycoalea, D.Z. Rivera, J. J. Onofre, K. Martinez, J. Lizardi; Tetrahedron, 2006, 62, 2520.
57. A. J. Cristu, J. L. Pirat, D. Birieux, J. Monbrum, C. Ciptadi. Y. A. Beko; J. Organomet. Chem., 2005, 690, 2472.
58. T. El-Sayed Ali; Arkivoc, 2008, 2, 71-79.
59. M. Maffei, G. Buono, Tetrahedron 2003, 59, 8821.
60. A. M. Pinhuk, A. S. Merkulov, G. V. Oshovsky, A. A. Tolmachas; Phosphorus, Sulfur and Silicon 1999, 144-146, 713.
61. a) C. Devendranath R., G. T. Reddy, C. N. Raju; Indian J. Heterocycl. Chem.., 1995, 4, 285). b. C. N. Raju, C. Das, G. S. Reddy; Indian J. Heterocycl. Chem., 1995, 4, 281.
62. C. Wodlin, M. G. Mollon; Anal. Chem., 1953, 25, 1168.
63. S. Motomizu, M. Oshima, A. Hirashima; Anal. Chim. Acta., 1988, 211, 119.
64. Xu M., Zhao W., Li B., Yang K. and Lin L., Synthesis of a phosphorus and sulfur-containing aromatic diamine curing agent and its application in flame retarded epoxy resins, Fire and Materials. doi: 10.1002/fam.2252, 2014.
65. Marta Fiedoruk, Elżbieta Mieczkowska, Robert Koncki, Łukasz Tymecki. A bimodal optoelectronic flow-through detector for phosphate determination. Talanta, 2014, 128(1), 211-214
66. V. Gerez, K. Rondano, C. E. L. Pasquali. A simple manifold flow injection analysis for determining phosphorus in the presence of arsenate Journal of Water Chemistry and Technology, 2014, 36(1), 19-24
67. S. Chakravarty, R. K. Mishra; J. Indian Chem. Soc., 1994, 71, 717.
68. R. M. Abdel-Rahman; Pharmazie, 1999, 54(11), 791.
69. R. M. Abdel-Rahman; Pharmazie, 2001, 56(4), 275.

---

This work is licensed under a Creative Commons Attribution 4.0 International License.