Stereogenic properties of spiranes combined with one or two equivalent conventional centres of chirality

Derivatives of the tri-spirane pentaerythritoxy-cyclophosphazene compound 1 have been used to investigate the stereogenic properties of spiranes combined with either one or two conventional centres of chirality. In compound 1, the two inner rings are carbocyclic and symmetrical and the two outer rings are cyclotriphosphazenes substituted in different positions to provide the conventional centres of chirality. Reaction of 1 in a 1:1 molar ratio with the unsymmetrical dinucleophilic reagent, 1,3-aminopropanol, gave the mono-spiro substituted derivative 2, which was shown to exist as a racemate by X-ray crystallography and ³¹P NMR spectroscopy on addition of a chiral solvating agent (CSA). Reaction of 1 with 1,3-aminopropanol in a 1:2 molar ratio gave three diastereoisomeric di-mono-spiro products 3a-3c, which were all shown to be racemates using a combination of X-ray crystallography (3a, 3c) and ³¹P NMR spectroscopy on addition of a CSA (3b), thus proving the case of the stereogenic properties of spirane molecules combined with two equivalent conventional centres of chirality. It is also shown by quantitative ³¹P NMR spectroscopy of the reaction mixture and by isolation of reaction products that the proportions of the diastereoisomers 3a:3b:3c are in approximate ratios of 1:2:1, respectively, and these results have been rationalised by analysis of the stereogenic properties of the series of reactions 1 → 2 → 3.     

Structural and thermosensitive properties of novel octopus shape cyclotriphosphazenes

Three novel compounds (3–5) were synthesized from the reactions of non-geminal cis-2,4,6 diethylene glycol monobutyl ether substituted cyclotriphosphazene (2a) with ethylamine, hexylamine and dodecylamine. Compounds 3–5 were characterized by ³¹P NMR, MS and elemental analysis. The thermosensitive properties of compounds 3–5 were investigated. Compound 3 showed thermosensitive properties which might enable it to be used as a biomedical material.     

19F,31P,1H NMR and X-ray crystallographic studies of (pentafluorophenyl)3−n (4-pyrazol-1-yl-2,3,5,6-tetrafluorophenyl) n=1,2,3 Phosphines

New phosphines1–3 have been synthetized by reaction of pyrazolate anion with tris(pentafluorophenyl)phosphine and characterized by¹H,³¹P, and¹⁹F NMR studies.¹⁹F NMR spectral data contribute to the evidence for apara-substitution of tetrafluorophenyl rings. The crystal structure of tris(4-pyrazol-1-yl-2,3,5,6-tetrafluorophenyl)phosphine 1 has been determined, proving that the assignment based on spectroscopic data was correct: C₂₇H₉F₁₂N₆P,M _r = 676.37, monoclinic, space group P2_l/c,a=10.754(2) å,b=10.316(2) å,c = 23.598(5) å,=95.36(3),V=2607(1), å³,Z=4,R ₁=0.042, andwR ₂=0.122.     

Investigation of homopolymerization rate of perfluoro-4,5-substituted-2-methylene-1,3-dioxolane derivatives and properties of the polymers

Five perfluoro-4,5-substituted-2-methylene-1,3-dioxolane monomers were synthesized. These monomers were found to readily polymerized by a free radical initiator in bulk and/or in solutions. Homopolymerization rates were determined using in situ ¹⁹F NMR measurements and found to be 0.25 to 1.66 × 10⁻⁴ mol L⁻¹ s⁻¹ in 1,1,2-trichlorotrifluoroethane at 41 °C using the perfluorodibenzoyl peroxide as an initiator. The rates depend on the substituents on the 4 and 5 positions of the dioxolane. The purified polymers were thermally stable (up to 350 °C). They show low refractive indexes (1.33-1.36 at 532 nm). They are transparent from UV to near IR region and have high glass transition temperatures (100-170 °C).     

Optimized synthesis of selected 4-oxybenzaldehyde and 2,2-dioxybiphenyl cyclotriphosphazene derivatives

Abstract

Selected 4-oxybenzaldehyde and 2,2-dioxybiphenyl cyclotriphosphazene derivatives were synthesized via substitution reactions through tailored control. The reactions of cyclotriphosphazene with 4-oxybenzaldehyde and 2,2-dioxybiphenyl gave the following synthesized derivatives: one mono-substituted open-chain compound, N₃P₃Cl₅(O₂C₇H₅) (1, 69%); mono spiro, N₃P₃Cl₄(O₂C1₂H₈) (2, 91.1%); non-gem tri-substituted, N₃P₃Cl₃ (O₆C₂₁H₁₅) (3, 17%); dispiro, N₃P₃Cl₂(O₄C₂₄H₁₆) (4, 92.3%); penta-substituted, N₃P₃Cl(O₁₀C₃₅H₂₅) (5, 92%);hexa-substituted, N₃P₃(O₁₂C₄₂H₃₀). Most of these derivatives (1–6) are obtained with good yield (up to 97%), This work provides a simple and available approach to obtain versatile cyclotriphosphazene derivatives, which is expected to further promote the use of HCCP as phosphorus platform for the construction of multi-functional materials.     

Synthesis and stereochemistry of some new 1,3,5-tris(1,3-dioxan-2-yl)-benzene derivatives

The synthesis and the stereochemistry of new 1,3,5-tris(1,3-dioxan-2-yl)-benzene derivatives are reported. The anancomeric structure and the axial orientation of the aryl group with respect to all 1,3-dioxane rings, and the cis-trans isomerism of some of the compounds are revealed. The data are supported by NMR investigations and by the molecular structure of one compound determined by single crystal X-ray diffractometry.     

The Phosphoenolpyruvate Phosphorylation: A Self-Organized Mechanism with Implications to Understand the RNA Transformations

In this article, we present a study about the non-enzymatic hydrolysis of phosphoenolpyruvate (PEP) by following the reaction course through ³¹P NMR spectroscopy. We have demonstrated that PEP in water exists mainly as a very stable cyclic pentacoordinate phosphorus compound in equilibrium with other cyclic forms. This explains the PEP stability in water. In contrast, after addition of an alcohol to a PEP aqueous solution, other very unstable cyclic pentacoordinated intermediates are formed, which immediately collapse, giving a feasible phosphorylation of the alcohol. It is known that cyclic pentacoordinated phosphorus intermediates are favored over the corresponding acyclic intermediates by a factor of 10⁶–10⁸, and this preference, found also in this study, might be the “driver mechanism” able to overcome the clutter of abiotic chemistry, thus permitting formation of pre-RNA molecules probably with a “self-organized process.”     

P,O-Ligands. Complexes of tetraphenylmethylenediphosphine oxide with silver nitrate

The 1 : 1 and 1 : 2 complexes of AgNO₃ with Ph₂PCH₂P(O)Ph₂ were prepared and their structures were established by IR and ³¹P NMR spectroscopy and X-ray diffraction analysis. The crystal of the 1 : 1 complex consists of centrosymmetric dimers based on the ten-membered macrocycle AgOPCH₂PAgOPCH₂P. Each neutral ligand serves as a bridge between two silver ions, the latter being coordinated by the NO₃ group in the monodentate fashion. In the 1 : 2 complex, the dimeric structure is retained, but both NO₃ groups are replaced by the ligand molecules.     

Aldehyde Functionalization in the Tetrathiafulvalene Series: Towards New Highly Dimensional Organic Materials Derived from Sulfur-Rich Extended π-Donors

Abstract

We describe the synthesis of giant analogs of TTF. Their powerful donor ability has been characterized by thin layer cyclic voltammetry. An unprecedented type of 2-D cation-radical salt has been obtained by electrooxidation.     

Synthesis,structure, and properties of organoplatinum(ii) derivatives of diphenyl ether

New mono- and disubstituted organoplatinum(II) derivatives of diphenyl ether,cis-(PhOC₆H₄-o)PtCl(PPh₃)₂ and (o-C₆H₄OC₆H₄-o)Pt(PPh₃)₂, were synthesized by the reaction of 2,2-dilithium diphenyl oxide withcis-Cl₂Pt(PPh₃)₂. Transmetallation of (PhOC₆H₄-o)AuPPh₃ withcis-Cl₂Pt(PPh₃)₂ was studied using³¹P NMR monitoring. This reaction proceeds with the retention of configuration to afford ClAuPPh₃ andcis-(PhOC₆H₄-o)PtCl(PPh₃)₂ under kinetically controlled conditions. The latter complex irreversibly isomerizes into thetrans isomer in the presence of equimolar quantities of ClAuPPh₃, whereas, in the presence of free PPh₃, this isomerization is reversible. The structures of the obtained diphenyl oxide derivatives of platinum were confirmed by³¹P NMR and FAB mass spectrometry. It was established by X-ray structural analysis that in thecis-(PhOC₆H₄-o)PtCl(PPh₃)₂ complex, the Pt atom is in a nearly square-planar coordination, and secondary intramolecular Pt...O interaction occurs.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1814–1820, October, 1994.We would like to thank A. L. Blyumenfel'd and P. V. Petrovskii for recording the 31p NMR spectra, and D. V. Zagorevskii and K. V. Kazakov for measuring the mass spectrometric characteristics.This work was supported by the International Science Foundation (Project No. MDV 000).     

The stereochemistry of a nine-membered ring analogue of nefopam,a nonnarcotic analgesic drug

The solid-state structure of a (±)-homonefopam hydrogenfumarate salt having an-O(CH₂)₃N-fragment was determined by single-crystal X-ray diffraction analysis. Homonefopam hydrogenfumarate gave crystals belonging to the monoclinicP2₁/c space group, and at ambient temperaturea=10.220(1),b=18.187(2),c=10.687(2)A,=94.43(1),V=1980.5(5)å³ Z=4,R(F)=0.039,R _w =0.039,R _W (F)=0.025. The¹H NMR spectrum of homonefopam hydrochloride in CD₂Cl₂ solution showed two species (7:1 ratio) at the prototropic shift-nitrogen inversion slow exchange limit. The solution-state major species has the same conformation andtrans-to-phenyl axial N-methyl disposition found in the crystal as evidenced by three antiperiplanar vicinal³ J (HH) coupling constants in the oxytrimethyleneamino fragment and vicinal coupling constants involving theN-H proton. TheR-ratio method was used to estimate 64(2) O-C(3)-C(4)-C(5) and 75(3) C(3)-C(4)-C(5)-N(6) dihedral angles for the major species in CD₂Cl₂ solution in accord with its proposed structure. The finding of C(3)-C(4) bond time-averaged magnitude³ J (HH) values and severe broadening of signals from other minor species protons suggests conformational heterogeneity for the solution-state minor species.     

Synthesis, crystal structure and non-linear optical properties of boronates derivatives of salicylideniminophenols

The condensation in one step of a series of salicylaldehydes and 2-amino-5-nitrophenol with 1-naphthylboronic acid, 2-naphthylboronic acid, and o-tolylboronic acid to give the corresponding boronates 1a-3a, 1b-3b and 1c-3d, is reported. The X-ray crystal structures of 1a, 2b and 3b allowed determining the α- and β-angle between the stilbene skeleton and the aryl or naphthylboronic fragments; these values are indicative of different conformations for the aryl moieties around the (B-C) boron-carbon bond which could potentially modulate the electronic properties on the boron stilbene compounds. All compounds were characterized by ¹H, ¹¹B and ¹³C NMR spectroscopy, UV, IR and mass spectrometry. Second- and third-order non-linear optical characterizations were also performed by EFISH and THG Maker Fringe techniques, respectively. Compounds 3a-3d containing an -N(Et)₂ donor group gave the best NLO response in second- and third-order.     

Study of the initial stages of alkoxo synthesis involving Ti(OBu)4 and cyclophosphites

The reactivities of cyclophosphite precursors in alkoxo syntheses involving titanium(iv) tetra(n-butoxide) were studied by ³¹P NMR and IR spectroscopy. 2-Diethylamido-4-methyl-1,3,2-dioxaphosphinane and 4-ethyl-2,6,7-trioxaphosphabicyclo[2.2.2]octane in benzene are inert toward Ti(OBu)₄. Gelation is accompanied by hydrolysis 2-diethylamido-4-methyl-1,3,2-dioxaphosphinane to give the corresponding hydrophosphoryl compound, while 4-ethyl-2,6,7-trioxaphosphabicyclo[2.2.2]octane remains intact during gelation.     

A Thermodynamic, 13C NMR,and 17O NMR Study of Isomeric 4,7-Dihydro-1,3-dioxepins and 4,5-Dihydro-1,3-dioxepins

The relative thermodynamic stabilities of 4,7-dihydro-1,3-dioxepin (4,6-dioxacycloheptene, 1a) and 4,5-dihydro-1,3-dioxepin (3,5-dioxacycloheptene, 1b), and of a number of their 2-substituted derivatives, have been determined by base-catalyzed chemical equilibration in DMSO solution. Without exception, the 4,5-dihydro isomer is the dominating species at thermodynamic equilibrium. The relative stability of the b form is promoted by the presence of a single alkyl group on C-2, whereas two alkyl groups on C-2 have an opposite effect. In general, the thermodynamic parameters H _m and _Sm , of isomerization vary unexpectedly with the pattern of substitution at C-2. These trends appear to be derived from significant substituent-induced conformational changes in the b isomer, as suggested by ¹³C and ¹⁷O NMR chemical shift data.     

(4R,5R)-Bis(N,N-dimethylaminocarbonyl)-2-chloro-1,3,2-dioxaphospholane: A convenient reagent for control of enantiomeric composition of chiral alcohols by31P NMR spectroscopy

The use of enantiomerically pure cyclic chlorophosphite obtained by the reaction of PCl₃ withN,N,N′,N′-tetramethyldiamide of naturall-(+)-tartaric acid for analysis of the enantiomeric composition of chiral primary and secondary alcohols by³¹P NMR spectroscopy is considered. Translated fromIzvestiya Akademii Nauk., Seriya Khimicheskaya, No. 1, pp. 172–175, January, 1998.     

Beryllium(II) Complexes with Bis(dimethylamino)phosphorylfluoride: A Multinuclear NMR (31P, 19F,and 9Be) Characterization in Solution

Complexes of beryllium chloride and nitrate with (Me₂N)₂P(O)F were characterized in solution by multinuclear NMR spectroscopy and in some cases by IR spectroscopy and conductimetry. ³¹P and ¹⁹F NMR spectra were informative of changes associated with complex formation revealing resonances consistent with different species in solution and suggest an equilibrium between these species in both beryllium derivatives. These compounds show narrow lines in the solution ⁹Be NMR spectra, indicative of a highly symmetric environment for beryllium. The presence of the different species was more pronounced in beryllium chloride complexes. The results are compared to those reported in the literature for hexamethylphosphoramide (HMPA).     

Phosphorus heterocycles: synthesis,spectroscopic study and X-ray crystallography of some new diazaphosphorinanes

New diazaphosphorinanes with formula R=C₆H₅O (2), 4-CH₃-C₆H₄NH (3), 4-NO₂-C₆H₄NH (4), R=Cl (5), 4-CH₃-C₆H₄O (6), and C₆H₅NH (7) were synthesized and characterized by ¹H, ¹³C, ³¹P NMR and IR spectroscopy and elemental analysis. The crystal structures of compounds 1 and (8) were determined using X-ray crystallography. In these structures, the P=O bond is placed in an equatorial position and the aliphatic six-membered rings show chair conformations. These compounds form two-dimensional polymeric chains via intermolecular P=O…H–N hydrogen bonds. ¹H NMR spectrum of compound 1 shows a ddd splitting pattern for the coupling of H_equatorial proton with phosphorus atom, H_axial atom, and NH proton with a high-value ³ J(PNCH) coupling constant = 26.1 Hz. But, H_axial indicates a dd splitting pattern because of the coupling with H_equatorial and NH protons. ¹³C NMR spectra of compounds 5–7, indicated high values for ³ J(P,C)_aromatic = 11.9, 11.3 and 10.2 Hz due to the coupling of the aromatic carbon atom of naphthalene moiety with the phosphorus atom. ³¹P NMR spectra indicate that the δ(³¹P) of compounds 1–4 and 8 containing NH groups connected to the aliphatic carbon atoms appear downfield relative to those of compounds 5–7 that containing NH groups connected to the aromatic naphthalene group.

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Graphical abstract

     

P,S-Ligands. Complexes ofP,P,P′,P′-tetraphenylethylenediphosphine monosulfide with PdCl2

1:1 and 1:2 complexes of Ph₂P(CH₂)₂P(S)Ph₂ with PdCl₂ were synthesized. Their structures were established by³¹P NMR and IR spectroscopy and X-ray diffraction analysis. In the crystals, the 1:1 complex has a chelate structure. In CH₂Cl₂, this complex partially dissociates at the Pd-.S=P bond. According to the X-ray diffraction data, only the P^III atoms the cationic chelate complex [Pd(Ph₂P(CH₂)₂P(S)Ph₂)₂]²⁺ 2NO₃ ⁻. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1122–1127, June, 2000.