Phospha-S-triazines. VIII. Chloro-substituted diphospha-S-triazines

1,3-Bis(phenylchlorophospha)-5-perfluoroalkyl-2,4,6- triazine and the corresponding perfluoroalkylether analogue were synthesized by interaction of equimolar amounts of the respective amidines and imido-diphenyl-diphosphinic acid pentachloride. With additional quantities of amidine, 1,3-bis(phenylperfluoro-$\text{n}$-octanoylamidinophospha)-5-perfluoro- $\text{n}$-heptyl-2,4,6-triazine was obtained. The replacement of the chloro- by azido-groups in 1,3-bis(phenylchlorophospha)-5- perfluoro-$\text{n}$-heptyl-2,4,6-triazine proceeded readily. The mass spectral breakdown patterns of the chloro- and the amidino- substituted compounds were directly comparable to those of the bis(diphenylphospha)-s-triazines.     

Phospha-s-triazines. IV. Degradation studies of 1-diarylphospha-3,5-bis(perfluoroaliphatic)-2,4,6-triazines and 1,3,-bis(diarylphospha)-5-perfluoroaliphatic-2,4,6-triazines

Thermal and thermal oxidative stability evaluations were performed on mono- and diphospha-s-triazines at 235 and 316°C using sealed Pyrex ampoules. The specific compounds studied were: 1-diphenylphospa-3,5-bis(perfluoro-n-heptyl)-2,4,6-triazine, 1-diphenylphospha-3,5-bis(perfluoro-alkylether)-2,4,6-triazines, their respective pentafluorophenyl analogues, 1,3-bis(diphenylphospha)-5-perfluoro-n-heptyl-2,4,6-triazine and 1,3-bis(diphenylphospha)-5-perfluoroalkylether-2,4,6-triazine. All the compounds wherein phenyl groups were present on the phosphorous exhibited good thermal stability up to 316°C; the analogous pentafluorophenyl substituted materials were degraded extensively at these temperatures. The oxidative stability of both the mono- and diphospha-s-triazines was excellent at 235°C, but at 316°C some degradation was observed. This was more pronounced in compounds containing the perfluoroalkyl moiety on carbon than in the perfluoroalkylether substituted members of the series.     

Phospha-s-triazines. I. Syntheses and properties of mono(diarylphospha)-s-triazines

A series of monophospha-s-triazines, namely l-diphenylphospha-3,5-bis(perfluoro-n-heptyl)-2,4,6-triazine, 1-diphenylphospha-3,5-bis[C₃F₇-[OCF(CF₃)CF₂]_xOCF(CF₃)]-2,4,6-triazine (x = 1 and 2), and the penta-fluorophenyl-substituted analogues were prepared, in yields of 50-75%, from the respective imidoylamidines and trichlorophosphoranes. The physical properties of the corresponding phenyl and pentafluorophenyl monophospha-s-triazines did not differ significantly; the perfluoroalkyl-substituted materials were low melting solids whereas the perfluoroalkyl-ether-containing compositions were liquids. Preliminary degradative studies showed these compounds to be thermally and oxidatively stable. The l-diphenylphospha-3,5-bis[C₃F₇OCF(CF₃)CF₂OCF(CF₃)]-2,4,6-triazine was found to be an effective anti-corrosion additive for perfluoroalkylether type fluids.     

Mass spectra of some perfluoroalkyl and perfluoroalkylether substituted 1,2,4-oxadiazoles

Electron impact fragmentation patterns were obtained for 1,4-bis[(5-perfluoro-n-heptyl)-1,2,4-oxadiazolyl]-benzene, its perfluoroalkylether substituted analogue, 3,5-bis(perfluoroalkyl)-, 3,5-bis(perfluoroalkylether)- and 3-perfluoroalkylether-5-perfluoroalkyl-1,2,4-oxadiazoles. In the compounds containing the phenylene group the molecular ion constituted the base peak; the main process was the breakdown of the oxadiazole ring with concurrent liberation of the perfluoroalkyl or perfluoroalkylether nitrile molecule; cleavage of the fluorinated chain α to the oxadiazole ring was found to take place to a considerable degree. In the perfluorinated 1,2,4-oxadiazoles cleavage β to the oxadiazole ring occurred preferentially; fragmentation of the ring itself took place to a limited degree only. The 3-perfluoroalkylether-5-perfluoroalkyl-1,2,4-oxadiazole appeared to undergo the primary β-cleavage exclusively at the perfluoroalkylether sidechain.     

New Approach to Synthesize Symmetrical and Unsymmetrical 6-(N-Alkyl(Aryl)Amino)- and 6-(N,N-Dialkyl(Aryl)Amino)-2,4-Bis(Alkyl(Aryl)Thio)Pyrimidines as anti-Platelet Agents

Abstract

A new and straightforward procedure has been developed for the preparation of symmetrical and unsymmetrical 6-(N-alkyl(aryl)amino)- and 6-(N,N-bisalkyl(aryl)amino)-2,4-bis(alkyl(aryl)thio)pyrimidines. The two identical or different alkylthio groups were successfully introduced into the pyrimidine ring of 4-amino-6-hydroxy-2- mercaptopyrimidine via S-alkylation with alkyl halides, and via a nucleophilic displacement with sodium alkylmercaptides, affording the key intermediate symmetrical and unsymmetrical 2,4-bis(alkyl(aryl)thio)-6-aminopyrimidines. Subsequently, N-alkylation of the 2,4-bis(alkyl(aryl)thio)-6-aminopyrimidines with alkyl halides conveniently gave the desired products. The human anti-platelet activities of all the synthesized new compounds were also evaluated.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

TRI (2-PYRIDYL) PHOSPHINE,TRI(2-PYRIDYL) PHOSPHINE OXIDE,AND TRI (2-PYRIDYL) ARSINE METAL (II) PERCHLORATE COMPLEXES

Abstract

Metal(II) perchlorate complexes with the ligands tri(2-pyridyl)phosphine, tri(2-pyridyl)phosphine oxide, and tri(2-pyridyl)arsine have the composition [M(TPX)₂] (ClO₄)₂. Coordination occurs only through the nitrogens of the pyridines. In the case of Cu(II) and tri(2-pyridyl)phosphine oxide, two isomers were obtained. One isomer contains symmetrical tridentate tri(2-pyridyl)phosphine oxide ligands while the second isomer contains an unsymmetrical ligand. The unsymmetrical tri(2-pyridyl)phosphine oxide may be a bidentate ligand or a bridging tridentate. Weak axial interaction between a pyridyl group and a second Cu(II) ion is postulated in solution and may be present in the solid state.     

Michael reaction of indoles with 3-(2′-nitrovinyl)indole under solvent-free conditions and in solution. An efficient synthesis of 2,2-bis(indolyl)nitroethanes and studies on their reduction

Michael reaction of 3-(2′-nitrovinyl)indole with eight 3-unsubstituted indoles on TLC-grade silica gel furnished unsymmetrical bis(indolyl)nitroethanes in 7-12 min under microwave irradiation and in 8-14 h at rt. In contrast, the p-TsOH-catalysed reaction of the nitrovinylindole with the 3-unsubstituted and two 3-substituted indoles in solution under reflux furnished both unsymmetrical and symmetrical bis(indolyl)nitroethanes, the latter resulting from novel tandem Michael addition-elimination-Michael addition reactions. The synthesis of a 2′,3″-bis(indolyl)nitroethane, the precursor core structure of two bioactive marine metabolites, and the reduction of 2,2-bis(3′-indolyl)nitroethane to the corresponding ethylamine, isolated as its N-acetyl derivative, have been achieved. Significantly, attempted hydrolysis of three nitronates, derived from the corresponding bis(indolyl)nitroethanes, with buffered aqueous TiCl₃ has led to the first isolation of oximes (syn/anti-mixture) as the only products.     

Syntheses and degradations of fluorinated heterocyclics II. Perfluoroalkyl and perfluoroalkylether-1,2,4-oxadiazoles

3-Perfluoroalkylether-5-perfluoro-n-heptyl-1,2,4-oxadiazole and 3,5-bis(perfluoroalkylether)-1,2,4-oxadiazole were synthesized and characterized. The 3,5-bis(perfluoroalkylether)-1,2,4-oxadiazole was subjected to thermal, thermal oxidative, and hydrolytic degradations at 235 and 325°C and was found to be stable under these conditions as evidenced by practically quantitative recovery of the test samples. In the presence of Jet-A-fuel at 235°C a low degree of degradation,～4%, was observed. 3,5-Bis(perfluoro-n-heptyl)-1,2,4-oxadiazole was found to be stable to attack by water at 325°C; however in air in the presence of Jet-A at 235°C the extent of degradation was in excess of 10%.     

Synthesis of new silylated sulfur-containing heterocycles through thionation of bis(acylsilanes)

The thionation of bis(acylsilanes) with spacers of variable size with hexamethyldisilathiane under cobalt(II) chloride or trimethylsilyl triflate catalysis affords 2,5-bis(trialkylsilyl)-thiophenes, 2,6-bis(trialkylsilyl)-4H-thiopyrans and 2,7-bis(trialkylsilyl)-4,5-dihydrothiepine generally along with a minor amount of the corresponding oxo analogue. The synthesis of both symmetrical and unsymmetrical bis(trialkylsilyl) derivatives was achieved.     

The synthesis of azabicyclic heterocycles

An efficient approach to a oxa-azabicyclo[3.2.1] derivatives has been achieved via a double-Mannich reaction of N,N-bis(methoxymethyl)-1-phenylethanamine with symmetrical and unsymmetrical ketones.     

New photochromic symmetrical and unsymmetrical bis(heteroaryl)maleimides: A spectrokinetic study

The photochromic behavior of two newly synthesized diarylethenes is here presented. The compounds studied are the symmetrical (1-benzyl-3,4-bis(2-methylbenzo[b]thiophen-3-yl)-[1H]-2,5-dihydropyrrol-2,5-dione) and the unsymmetrical (1-benzyl-3-(2-methylbenzo[b]thiophen-3-yl)-4-(2,5-dimethyl-3-thienyl)-[1H]-2,5-dihydropyrrol-2,5-dione). Upon stimulation with UV or violet light, these compounds become red-colored due to photocyclization and cyclorevert to the light yellow open form upon irradiation with visible light. In this work, absorption and fluorescence spectra, molar absorption coefficients of the ethenic and cyclized forms, fluorescence quantum yields and photochemical quantum yields of both the forward and back photoreactions were determined. Temperature, excitation wavelength and solvent effects were explored. The symmetrical compound was found to be a bistable photochrome. In contrast, the unsymmetrical molecule resulted unsuitable as photochrome because of side degradation processes occurring in competition with cyclization.     

Iodonium Cation-Pool Electrolysis for the Three-Component Synthesis of 1,3-Oxazoles

The synthesis of 1,3-oxazoles from symmetrical and unsymmetrical alkynes was realized by an iodonium cation-pool electrolysis of I₂ in acetonitrile with a well-defined water content. Mechanistic investigations suggest that the alkyne reacts with the acetonitrile-stabilized I⁺ ions, followed by a Ritter-type reaction of the solvent to a nitrilium ion, which is then attacked by water. The ring closure to the 1,3-oxazoles released molecular iodine, which was visible by the naked eye. Also, some unsymmetrical internal alkynes were tested and a regioselective formation of a single isomer was determined by two-dimensional NMR experiments.     

Syntheses and electronic properties of the nickel and palladium complexes of the octaethylporphyrin(M1)-(dihexylbithiophene)n-octaethylporphyrin(M2) system [OEP(M1)-(DHBTh)n-OEP(M2)] connected with the diacetylene linkage. A methodology for molecular design of the particular electronic structure

The palladium complexes of highly extended π-electronic conjugation system, octaethylporphyrin(Pd)-(dihexylbithiophene)_n-octaethylporphyrin(Pd) [OEP(Pd)-(DHBTh)_n-OEP(Pd), n=1-6], were synthesized, in which all the chromophores are connected with diacetylene linkage. The unsymmetrical derivatives of OEP(Ni)-DHBTh-OEP(Pd) were also successfully synthesized. Electronic properties of these symmetrical and unsymmetrical complexes were conclusively described, as compared with those of OEP(Ni)-(DHBTh)_n-OEP(Ni). Based on the structure elements, a methodical guiding principle for molecular design of the particular electronic structure will be proposed.     

Mass spectra of perfluoroalkyl and perfluoroalkylether nitriles and acyl halides

Electron impact fragmentation patterns were obtained for perfluoroalkylether nitriles, C,F,O[CF(CF₃)CFIO]ICF(CF₃)CN (x = 1 and 2), perfluoroalkylether acyl halides, CSF,OCF(CF,)-CF₂OCF(CF₃)COX (X = F and Cl), n-perfluorooctanonitrile and n-perfiuorooctanoyl chloride. The perfluoroalkyl and perfluoroalkylether nitriles afforded ions characteristic of the nitrile function. The major fragment from the acyl chlorides was the [COClJ]+ ion; the presence of chlorine was evidenced also by rearrangement ions of the general form [R_fCl] t. The perfluoroalkylether compounds appeared to undergo a typical fragmentation governed by the cleavage of the carbon-oxygen bond.     

Phospha-S-triazines. IX. Chloro-substituted monophospha-S-triazines and derivatives

1-Dichlorophospha-3,5-bis(perfluoro-n-heptyl)-2,4,6- triazine and one of its perfluoroalkylether analogues were synthesized by interaction of phosphorus pentachloride with the respective imidoylamidines; subsequent replacement of the chloro- by azido groups proceeded readily. 1-Chloro(phenyl)- phospha-3,5-bis(perfluoro-n-heptyl)-2,4,6-triazine was prepared by a parallel process using tetrachlorophenylphosphorane instead of phosphorus pentachloride; phenoxy and stearyloxy derivatives were formed without difficulty. All the compounds, with the exception of 1-stearyloxy(phenyl)phospha-3,5-bis(perfluoro- n-heptyl)-2,4,6-triazine, exhibited the characteristic mass spectral fragmentation patterns associated with the monophospha- s-triazine ring system.     

Mirabiquinone,a new unsymmetrical binaphthoquinone from the sea urchin Scaphechinus mirabilis

Mirabiquinone [7,5′-anhydroethylidene-6,6′-bis(2,3,7-trihydroxynaphthazarin)], a new unsymmetrical binaphthoquinone, was isolated from the sea urchin Scaphechinus mirabilis along with the known symmetrical binaphthoquinones ethylidene-6,6′-bis(2,3,7-trihydroxynaphthazarin) and 7,7′-anhydroethylidene-6,6′-bis(2,3,7-trihydroxynaphthazarin). The structure of mirabiquinone was established using ¹H NMR, ¹³C NMR, HSQC and HMBC data, along with a spectroscopic analysis of its pentamethoxy derivative. Mirabiquinone and the symmetrical binaphthoquinones demonstrated excellent scavenging of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical.     

Cyclic 1,1-bis(silyl)alkenes—new building blocks for the stereoselective synthesis of unsymmetrical (E)-stilbenes and (E,E)-1,4-diarylbuta-1,3-dienes

A new efficient synthetic protocol for the highly stereoselective synthesis of unsymmetrical (or symmetrical) (E)-stilbenes and (E,E)-1,4-diarylbuta-1,3-dienes based on sequential palladium-catalyzed Heck arylation-Hiyama cross-coupling reactions using cyclic gem-bis(silyl)ethene as alkenyl building block is reported.     

Borane-catalyzed selective dihydrosilylation of terminal alkynes: reaction development and mechanistic insight

Here, we describe simple B(C₆F₅)₃-catalyzed mono- and dihydrosilylation reactions of terminal alkynes by using a silane-tuned chemoselectivity strategy, affording vinylsilanes and unsymmetrical geminal bis(silanes). This strategy is applicable to the dihydrosilylation of both aliphatic and aryl terminal alkynes with different silane combinations. Gram-scale synthesis and conducting the reaction without the exclusion of air and moisture demonstrate the practicality of this methodology. The synthetic utility of the resulting products was further highlighted by the structural diversification of geminal bis(silanes) through transforming the secondary silane into other silyl groups. Comprehensive theoretical calculations combined with kinetical isotope labeling studies have shown that a prominent kinetic differentiation between the hydrosilylation of alkynes and vinylsilane is responsible for the chemoselective construction of unsymmetrical 1,1-bis(silanes).

A B(C₆F₅)₃/silane-based system enables the chemoselective dihydrosilylation of terminal alkynes. Using a combination of different types of hydrosilanes, a series of unsymmetrical or symmetrical 1,1-bis(silanes) could be constructed.     

Structure and intramolecular hydrogen bonds in Bis(trifluoromethylsulfonylamino)methane and N-[(trifluoromethylsulfonyl)aminomethyl]acetamide

Bis(trifluoromethylsulfonylamino)methane in an inert medium exists as an equilibrium mixture of monomeric forms with various types of intramolecular hydrogen bonds, whose population depends on the polarity of the medium. The energetically most favorable form is a symmetrical form containing two N-H...O=S bonds. Less stable are the isomer with two N-H...F-C bonds and the unsymmetrical isomer with two different hydrogen bonds. N-[(Trifluoromethylsulfonyl)aminomethyl]acetamide contains one intramolecular intramolecular N-H...O=C hydrogen bond and preserves ability for self-association.     

Hexafluoraceton als Schutzgruppen-und Aktivierungsreagenz in der Aminosäure-und Peptidchemie, 11. Mitt.: Ein neuer präparativ einfacher Zugang zu 2,5-Dioxopiperazinen und 2,5-Dioxomorpholinen

Summary 2,5-Dioxopiperazines with symmetrical as well as unsymmetrical substituent pattern can be obtained via 2,2-bis(trifluoromethyl)-1,3-oxazolidin-5-ones, and 2,5-dioxomorpholines via 2,2-bis-(trifluoromethyl)-1,3-dioxolan-4-ones, respectively.

Herrn Prof. Dr. Wolfgang Beck, Anorganisch-Chemisches Institut der Universität München, mit den besten Wünschen zum 60. Geburtstag gewidmet.