Electrochemical properties of bis(pyrylium) salts containing a phenylene bridge

Bis(pyrylium) cations were obtained by the condensation of methyl-substituted pyrylium salts with terephthalic dialdehyde. Their electrochemical reduction in dimethylformamide was studied by cyclical volt-amperometry on a platinum disk electrode. The reduction of compounds of the bis(pyrylium) series proceeds in two steps with the formation of cation radicals in the first step and a neutral quinoid particle in the second step.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 460–464, April, 1990.     

A novel synthesis of reactive polymers with pendant halomethyl groups by the polyaddition reaction of bis(epoxide)s with bis(chloroacetoxy)esters or bis(bromoacetoxy)esters

New reactive polymers with pendant halomethyl groups were successfully synthesized by polyaddition reactions of bis(epoxide)s with bis(chloroacetoxy)ester such as 1,4-bis [(chloroacetoxy)methyl]benzene (BCAMB) or 1,4-bis[(bromoacetoxy)methyl]benzene (BBAMB) using quaternary onium salts or crown ether complexes as catalysts. The polyaddition reaction of diglycidyl ether of bisphenol A (DGEBA) with BCAMB proceeded very smoothly with high yields (83–96%) by the addition of quaternary onium salts such as tetrabutylphosphonium bromide (TBPB) or crown ether complexes such as 18-crown-6/KBr as catalysts to produce high molecular weight polymers, although the reaction occurred without any catalyst to give low molecular weight polymer in low yield at 90°C for 48 h. It was also found that the reaction proceeded smoothly in aprotic polar solvents such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc) to produce high molecular weight polymers. Polyaddition reactions of DGEBA or digylcidyl ether of ethylene glycol (DGEEG) with BBAMB, other bis(chloroacetoxy)esters or bis(bromoacetoxy)esters using TBPB in DMAc also proceeded smoothly to give the corresponding polymers. The resulting poly(ether-ester)s contain reactive halomethyl groups as side chains, which were introduced during main chain formation. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3791–3799, 1997     

On the reaction of orsellinic acid carbanion with pyrylium salts

From the reaction of methyldimethyl orsellinate anion $\text{1}$ with the pyrylium salt $\text{2}$ the isocoumarin $\text{5}$ was isolated in addition to the pyrones $\text{3}$ and $\text{4}$. Reaction intermediates could be trapped as pyridines $\text{6}$ and $\text{7}$.     

Sulfur-containing polymers. V. Preparation of polyoxycarbonylsulfenamides by polycondensation of bis(oxycarbonylsulfenyl chlorides) with diamines

Polyoxycarbonylsulfenamides (POSA) have been prepared by interfacial polycondensation of bis(oxycarbonylsulfenyl chlorides) with diamines. The polymers obtained ranged in physical form from crystalline solids to resinous materials depending on the kind of both bis(oxycarbonylsulfenyl chlorides) and diamines used. Some of the polymers gave transparent pliable films from chloroform solution. The polymer films decomposed with liberation of carbonyl sulfide on being subjected to ultraviolet radiation.     

Recyclization of indolo[2,3-c]pyrylium salts by reaction with secondary amines

1-R-3-methylindolo[2,3-c]pyrylium salts react with cyclic secondary amines (morpholine, piperidine, and N-methylpiperazine) to give, depending on the structure of the alkyl substituent R, either 1- (when R=Me) or 3-aminocarbazoles (when R=i-Pr), or mixtures of both (when R=Et). The position of the amino-substituent in 1-morpholino-3,9-dimethylcarbazole has been established by x-ray diffraction examination.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 546–551, April, 1990.     

A novel synthesis of indolines by reaction of ortho-nitrophenylmalonates with bis(dimethylamino)methane

We report here a new and efficient synthesis of substituted indolines via reaction of dimethyl 2,4-dinitrophenyl-(2,4,6-trinitrophenyl)malonates with bis(dimethylamino)methane.     

Synthesis of pyrimidine derivatives by reaction of pyrylium salts with guanidine and compounds of the guanidine series

2,4,6-Triphenylpyrylium perchlorate reacts with methylguanidine to give 1-methyl-2-amino-4,6-diphenylpyrimidinium perchlorate, which undergoes the Dimroth rearrangement to give 2-methylamino-4,6-diphenylpyrimidine. 2,4,6-Triarylpyrylium perchlorates react with guanidine to give N-pyrimidinylpyridinium salts. Pyrylium salts react with aminoguanidine, sulfanilylguanidine, and symmetrical diphenylguanidine at one amino group to give the corresponding pyridinium salts. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 748–752, June, 1980.     

A metal-free approach to the synthesis of indoline derivatives by a phenyliodine(III) bis(trifluoroacetate)-mediated amidohydroxylation reaction

A novel approach to the synthesis of indoline derivatives is presented. The key cyclization step features the phenyliodine(III) bis(trifluoroacetate)- (PIFA-) mediated formation of a N-acylnitrenium ion and its succeeding intramolecular trapping by the olefin fragment. In addition, difunctionalization of the alkene moiety is achieved since the in situ generation of an additional hydroxy group at the terminal position of the original double bond accompanies the intramolecular C-N bond formation.     

Polyaddition of bis(seven‐membered cyclic carbonate) with diamines: A novel and efficient synthetic method for polyhydroxyurethanes

This article deals with the polyaddition of a novel bis(seven‐membered cyclic carbonate), 1,2‐bis[3‐(1,3‐dioxepan‐2‐one‐5‐yl)‐propylthio]ethane, with the diamines 4,9‐dioxa‐1,12‐dodecanediamine and p‐xylylenediamine. The polyaddition was carried out at 30–70 °C for 6–24 h in dimethyl sulfoxide to obtain the corresponding polyhydroxyurethanes with number‐average molecular weights of 10,900–35,700 in good yields. The reaction of a monofunctional seven‐membered cyclic carbonate, 5‐allyl‐1,3‐dioxepan‐2‐one (7CC), with monoamines was also carried out to examine the reactivity in comparison with that of six‐ and five‐membered cyclic carbonates. The reaction rate constants of 7CC with n‐hexylamine and benzylamine were estimated to be 48.5 and 11.0 L/mol · h, respectively, in dimethyl sulfoxide‐d₆ (initial reagent concentration = 1 M) at 30 °C. The seven‐membered cyclic carbonate ring was 2.98 and 5.82 kcal/mol more strained than those of the six‐ and five‐membered cyclic carbonates, respectively, according to a semiempirical molecular orbital calculation with the PM3 Hamiltonian. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4091–4100, 2001     

A novel approach to the synthesis of amino acids based on cobalt bis(dicarbollide)

A novel approach to the synthesis of boron-containing amino acids based on ring opening of cyclic oxonium derivatives of polyhedral boron hydrides under the action of the terminal functional groups of natural amino acids was proposed. This approach was successfully implemented for the synthesis of cobalt bis(dicarbollide) — tyrosine conjugate.     

Improved synthesis of pyrylium salts leading to 2,4-disubstituted diarylfurans via novel mechanism

Improved synthesis of pyrylium salts from either substituted benzoic acids or their methyl esters, and substituted acetophenone is reported en route to the synthesis of 2,4-diarylfurans. The mechanism involved in the formation of the pyrylium salt using these starting materials is proposed.     

Synthesis and polymerization of novel formamidinium salts: A new pathway to polyamides derived from aromatic diamines

A new polycondensation pathway has been developed for the preparation of polyamides at high temperatures. p-Phenylenediamine was converted to N,N-p-phenylene bis(N′,N′-dimethylformamidine) (I), which formed 1–1 and 2–1 salts with terephthalic and adipic acids, respectively: Dicarboxylate salts were polymerizable by heating in bulk or suspension. Low-molecular-weight poly(p-phenyleneterephthalamide) was obtained from N,N-p-phenylene bis(N',N'-dimethylformamidinium) terephthalate above 225°C. The low degree of polymerization was due to terephthalic acid sublimation as well as to the well-known intractability of poly(p-phenyleneterephthalamide). High-viscosity poly(p-phenyleneadipamide) was obtained from N,N-p-phenylene bis(N′,N′-dimethylformamidinum hydrogen adipate) above 200°C. Both salts liberated dimethylformamide (DMF) during polymerization. The adipate salt also released 1 mole of adipic acid during the high-temperature vacuum stage of polymerization. A polycondensation mechanism was proposed for each salt, based on thermal gravimetric analysis (TGA-MS) and infrared (IR) analyses. The hydrolysis of N,N-p-phenylene bis(N',N'-dimethylformamidine), N,N-p-phenylene bis(N',N'-dimethylformamidinium chloride), and the two dicarboxylate salts of (I) was monitored by nuclear magnetic resonance (NMR) at room temperature. The dihydrochloride salt was most resistant to hydrolysis (k_H 6.9 × 10^?9 sec^?1; relative rate 1.0) followed by (I) 7.1, terephthalate salt, 14.9, and adipate salt, 27.2. Both dicarboxylate salts possessed sufficient hydrolytic stability for use as polycondensation monomers     

Study of the reaction of methyltris(dimethylamino)silane with diamines

Tris(dimethylamino)methylsilane reacts with N,N′-dialkyldiamines to give the corresponding substituted 1,3,2-diazasilacycloalkanes. In contrast, the reaction with an N-alkyldiamine yields the corresponding polycyclic silazane.     

Synthesis of pyridine and pyrimidine derivatives by reaction of pyrylium salts with ureas,thioureas, and isothioureas

2,4,6-Triphenylpyrylium perchlorate is converted to 2,4,6-triphenylpyridine in reactions with urea and N-acetyl- and N,N-dimethylureas, whereas it is converted to 1,2,4,6-tetraphenylpyridinium perchlorate on reaction with N,N-diphenylurea. The reaction of pyrylium perchlorates with thiosemicarbazide and semicarbazide leads to 1-thiocarbamido- and 1-carbamidopyridinium salts. The latter reacts with 2,4,6-triphenylpyrylium perchlorate to give 1-aminopyridinium salts, which were acylated with acetic anhydride. Difficult-to-obtain 2-alkylthio-4,6-diarylpyrimidines were synthesized in 40–93% yields by the reaction of 2,4,6-triarylpyrylium salts with S-alkylisothioureas.Translated from Khuniya Geterotsiklicheskikh Soedinenii, No. 3, pp. 324–328, March, 1979.