Efficient Protocol for Synthesis of β-Hydroxy(alkoxy)selenides via Electrochemical Iodide-Catalyzed Oxyselenation of Styrene Derivatives with Dialkyl(aryl)diselenides

An efficient protocol for the synthesis of β-hydroxy(alkoxy)selenides was developed through the electrochemical iodide-catalyzed oxyselenation of styrene derivatives with dialkyl(aryl)diselenides under mild reaction conditions. Mechanistic studies showed that the cation I⁺ is involved during the whole process, and accelerates the formation of seleniranium ion via substitution and addition reaction with dialkyl(aryl)diselenides and styrene derivatives. The corresponding products are formed in good to excellent yields. This electrochemical oxyselenation provides an efficient strategy for difunctionalization of alkenes.     

Base‐Catalyzed Formation of Isoxazoles from Dialkyl Acetylenedicarboxylates and 2‐Nitroacetophenones

The reaction of dialkyl acetylenedicarboxylates with 1‐aryl‐2‐nitroethanones in the presence of pyridine leads to dialkyl 5‐aryloyl‐isoxazole‐3,4‐dicarboxylates through a novel mechanism, which involves a [2+2] cycloaddition/ring opening/cyclization sequence.     

Stereoselective Synthesis of Dialkyl 2-(Arylsulfonylamino)-3-(dialkoxyphosphoryl) Succinates by Reaction of Trialkyl(aryl) Phosphites,Dialkyl Acetylenedicarboxylates,and Arylsulfonamides

A three-component reaction of trialkyl(aryl) phosphites, dialkyl acetylenedicarboxylates, and arylsulfonamides is described as a simple and efficient route for the synthesis of dialkyl 2-(arylsulfonylamino)-3-(dialkoxyphosphoryl)-succinates in good yields.

A Stereospecific Synthesis of Dialkyl(Aryl)-2-Nitroeth-1-Enylphosphonates and their Reactions with Non-Carbon Nucleophiles

Abstract

Dialkyl l-alkyl(aryl)-2-nitroen-l-enylphosphonates (1) are the important intermediate for the synthesis of functionalized phosphonic acids owing to the presence of reactive alkene and nitrogroups. It was expected that nucleophilic addition and subsequent reduction would result 2-aminólkyl phosphonic acid derivatives. On the other hand, conversion of nitrogroup into silylnitronate as reactive 1,3-dipole provides new synthetic route to phosphoryl isoxazoles. Compounds 1 were prepared by treatment of dialkyl 1 -alkyl(aryl) -1 -hydroxy-2-nitrólkylphosphonates with thionyl chloride and pyridine. The dehydration process underwent stereospecifically providing exclusive E-ismers. An E2 reaction mechanism is suggested.     

A New Route for the Synthesis of Dialkyl Tellurides and Dialkyl Ditellurides

Sodium cleaves elemental tellurium, Te_X, quantitatively to Te^2– ₂ and Te^2- in anhydrous tetrahydrofuran in the presence of catalytic amounts of naphthalene. Subsequent addition of alkylating agent affords dialkyl tellurides and dialkyl ditellurides in excellent yields.     

Efficient Synthesis of Dialkyl (2Z)‐2‐[(E)‐1‐Aryl‐2‐(3‐arylquinoxalin‐2‐yl)ethenyl]but‐2‐enedioates

The reaction of dialkyl acetylenedicarboxylates 4 with 1‐aryl‐2‐[(3‐arylquinoxalin‐2(1H)‐ylidene)ethanones 3 in the presence of Ph₃P leads to dialkyl (2Z)‐2‐[(E)‐1‐aryl‐2‐(3‐arylquinoxalin‐2‐yl)ethenyl]but‐2‐enedioates 1 in good yields.     

Investigation of the addition of dialkyl(aryl)phosphine oxides to alkyl(aryl)vinyldialkoxysilanes

Conclusions Alkyl(aryl){2-[dialkyl(aryl)phosphoryl]ethyl}dialkoxysilanes were obtained as a result of addition of dialkyl(aryl)phosphine oxides to alkyl(aryl)vinyldialkoxysilanes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 183–186, January, 1985.     

Microwave Irradiation Technique for Synthesis of Dialkyl Dithiophosphoric Acids

Microwave heating technique was applied to the preparation of dialkyl dithiophosphoric acids from the reaction of alcohol with phosphorus pentasulphide. A microwave oven (CEM-MDS 2000) was utilized to determine the preparation conditions for the best yield of dialkyl dithiophosphoric acids under atmospheric pressure at various times and power. Six different (C 4 -C 9 ) chain-length of dialkyl dithiophosphoric acids were studied. All experiments were performed in an open Teflon (poly-tetrafluoroethylene) vessel. The results obtained showed that the reaction of dialkyl dithiophosphoric acids can be achieved more rapidly using microwave heating than using conventional procedures.     

[NiCl2(dppp)]‐Catalyzed Cross‐Coupling of Aryl Halides with Dialkyl Phosphite,Diphenylphosphine Oxide,and Diphenylphosphine

We present a general approach to C? P bond formation through the cross‐coupling of aryl halides with a dialkyl phosphite, diphenylphosphine oxide, and diphenylphosphane by using [NiCl₂(dppp)] as catalyst (dppp=1,3‐bis(diphenylphosphino)propane). This catalyst system displays a broad applicability that is capable of catalyzing the cross‐coupling of aryl bromides, particularly a range of unreactive aryl chlorides, with various types of phosphorus substrates, such as a dialkyl phosphite, diphenylphosphine oxide, and diphenylphosphane. Consequently, the synthesis of valuable phosphonates, phosphine oxides, and phosphanes can be achieved with one catalyst system. Moreover, the reaction proceeds not only at a much lower temperature (100–120 °C) relative to the classic Arbuzov reaction (ca. 160–220 °C), but also without the need of external reductants and supporting ligands. In addition, owing to the relatively mild reaction conditions, a range of labile groups, such as ether, ester, ketone, and cyano groups, are tolerated. Finally, a brief mechanistic study revealed that by using [NiCl₂(dppp)] as a catalyst, the Ni^II center could be readily reduced in situ to Ni⁰ by the phosphorus substrates due to the influence of the dppp ligand, thereby facilitating the oxidative addition of aryl halides to a Ni⁰ center. This step is the key to bringing the reaction into the catalytic cycle.     

Phase-Transfer-Catalyzed Michaelis-Becker Synthesis of Dialkyl Methyl Phosphonates

A liquid–liquid phase-transfer-catalyzed (PTC) Michaelis-Becker reaction was adopted in the preparation of dialkyl methyl phosphonate (R = Me, iPr, nBu, and iBu). This was performed by the reaction of an appropriate dialkyl hydrogen phosphonate with methyl iodide in the presence of benzyl triethyl ammonium chloride and sodium hydroxide as PTC and base, respectively. A liquid–liquid two-phase system (H₂O/CH₂Cl₂) introduced a suitable situation for the preparation of dialkyl methyl phosphonates with bulky alkyl groups (R = iPr, nBu, and iBu), but with R = Me, the hydrolysis of dimethyl hydrogen phosphonate (reagent) reduced the yield to 22%. In this case, a solid–liquid PTC-free system was successfully applied and yield of over 80% was obtained.     

Dialkyl Ether Formation by Nickel‐Catalyzed Cross‐Coupling of Acetals and Aryl Iodides

A new substrate class for nickel‐catalyzed C(sp³) cross‐coupling reactions is reported. α‐Oxy radicals generated from benzylic acetals, TMSCl, and a mild reductant can participate in chemoselective cross‐coupling with aryl iodides using a 2,6‐bis(N‐pyrazolyl)pyridine (bpp)/Ni catalyst. The mild, base‐free conditions are tolerant of a variety of functional groups on both partners, thus representing an attractive C? C bond‐forming approach to dialkyl ether synthesis. Characterization of a [(bpp)NiCl] complex relevant to the proposed catalytic cycle is also described.     

Synthesis of Nitro Compounds Starting with Dialkyl Aminomalonates

By reaction of dialkyl aminomalonates with formaldehyde were prepared 1,3,5-tris(dialkoxycarbonylmethyl)hexahydro-1,3,5-triazines that on nitration under mild conditions yielded the corresponding nitromethyl derivatives. The reaction of dialkyl aminomalonates with formaldehyde and polynitroalkanes operating as C-H acids results in Mannich bases. The latter were subjected to nitration with mixtures of sulfuric and nitric acids to afford dimethyl and diethyl 2,2,2-polynitroalkylnitroaminonitromalonates.     

Convenient Synthesis of Dialkyl 1‐Azidoalkylphosphonates using Tetramethylguanidinium Azide as Azidation Agent

A simple and safe method for the preparation of dialkyl 1‐azidoalkylphosphonates from dialkyl 1‐(4‐nitrobenzenesulfonyloxy)alkylphosphonates (dialkyl 1‐(nosyloxy)alkylphosphonates) and tetramethylguanidinium azide (TMGA) has been developed.     

On triazoles. XXII. Synthesis of Dialkyl (3-Q-1,2,4-triazol-5-yl)iminodithiocarbonates

Isomeric dialkyl and diaralkyl[1-, 2- and 4-(alkyl, aralkyl and aryl)-3-Q-1,2,4-triazole-5-yl]iminodithiocarbonates 4a-c (R ≠ H) were synthesised and their spectral data compared. The uv, cmr and ms rules elaborated helped to prove the tautomeric structure of the non-substituted derivatives 4 (R ? H). In case of dimethyl (3-methylthio-1,2,4-triazole-5-yl)iminodithiocarbonate this is the first time ever crystalline triazole desmotropes 4a/17 and 4b/17 could be isolated. The sodium salts of 4 (R ? H) could be further alkylated and aralkylated to yield the corresponding 4 (R ? alkyl and aralkyl) type derivatives. Providing the above reaction in the presence of carbon disulfide the dithiocarbomethoxy derivative 7 was obtained.     

Synthesis of Dialkyl Phosphoroselenocyanatidates and Their Rearrangement to Dialkyl Phosphoroiso-selenocyanatidates

The synthesis of diaryl and dialkyl phosphoroisoseleno-cyanatidates (I) has been described only recently^1,2. However, their isomers, dialkyl or diaryl phosphoro-selenocyanatidates (II) are, to our knowledge, unknown. In our attempts of their synthesis we found that the preparation of II in the way analogous to the synthesis of the corresponding thiocyanatidates ³was not possible due to the inaccessibility of the 0,0-dineopentoxy-oxo-phosphoraneselenenyl chloride (III). Reaction of triethylamminium 0,0-dineopentyl-phosphoroselenoate (IVa) with sulphuryl chloride at -70[ddot]C in CH₂Cl₂ solution led     

The Synthesis and Properties of Some Fluorinated Dialkyl Phosphoramidates

The synthesis and physical properties of the first fluorinated dialkyl phosphoramidates of structure (RCH 2 O) 2 P(O)NHCH 2 R F , where R = CH 3 , CF 3 or CCl 3 and R F = CF 3 or C 2 F 5 , are described. They were obtained by treatment of the respective dialkyl phosphorochloridates with trifluoroethylamine or pentafluoropropylamine in ether in the presence of triethylamine.     

Novel Rearrangements of 2,3-Dimercapto-1-propanol Derivatives: Formation of Dialkyl Sulfide, Dialkyl Disulfide, and 1,2,3-Tris(alkylthio)propane

The base alkylation of 2,3-dimercapto-1-propanol with alkyl halides leads in good yield to 2,3-bis(alkylthio)-1-propanol and dialkyl sulfide. The reaction of 2,3-bis(alkylthio)-1-propanol with catalytic concentrated sulfuric acid proceeds with rearrangement to give 1,2,3-tris(alkylthio)propane and dialkyl disulfide. The rearrangement reaction takes place through a common intermediate thiaranium intermediate 8.     

Diazoalkanes in the Reactions with Dialkyl (Thio)-Phosphites

Abstract

The photochemical, thermo-catalytical and thermal reactions of diazoalkanes with dialkyl (thio)phosphites were studied.

Thus, the photolysis of dimethyldiazomalonate and methyl-diazoacetate with dialkyl(thio)phosphites gives P-H insertion products only upon triplet-sensitized conditions (i), whereas diphenyldiazomethane gives P-H insertion products upon direct photolysis as well (ii). The investigation of 31 the reaction mechanism is based on CIDNP ³¹P method. The catalytical reactions (iii) are a convenient method of preparing (thio)phosphonates.     

Dialkyl dichalcogen cations

One electron oxidation of dialkyl diselenides and ditellurides is achieved with NO(+)CF(3)SO(3)(-). According to ab initio calculations the radical cations have a trans stucture. In the solid state they dimerize to rectangular units [R-Te](4)(2+) and [R-Se](4)(2+). The long SeSe and TeTe bond is obviously due to a pi*-pi* interaction.