Investigations in the 1,2,4-triazole series

To select a method for the synthesis of the previously difficulty accessible 5-bromo-1-phenyl-1,2,4-triazole (I) and 1-phenyl-1,2,4-triazoline-5-thione (II), a MO LCAO calculation has been carried out in Huckel's approximation of the energies of the radical, electrophilic, and nucleophilic localization on the various carbon atoms of 1-phenyl-1,2,4-triazole (III). In accordance with this calculation, the required compounds have been obtained in good yields by reactions taking place by a radical mechanism: I by bromination with bromosuccinimide and II by the direct thionation of III. The high reactivity of the bromine atom in position 5 has been noted.For part VIII, see [1].     

Effect of chain length on radical to carbanion cyclo-coupling of bromoaryl alkyl-linked oxazolines: 1,3-areneotropic migration of oxazolines

2-Halophenylalkyl-2-oxazolines with alkyl chain spacers of two to six C atoms (n = 0-4) were prepared and their SRN1-type reactions with several base systems examined. The best conditions to promote cyclo-coupling to the corresponding benzocycloalkane derivatives involved use of LDA in THF. The precursors with 3-C-atom and 4-C-atom spacers gave good yields of 2-(1'-phenylindan-1'-yl)-2-oxazolines and 2-(1-phenyl-1,2,3,4-tetrahydronaphthalen-1-yl)-2-oxazoline, respectively. The major products from the precursor with a 5-C-atom spacer were derivatives of benzocycloheptane in which the oxazoline group had undergone a novel areneotropic migration from the end of the spacer to the benzo ring. The product from reaction of the corresponding 2-C-atom precursor was a 9-oxazolinophenanthrene derivative. EPR spectroscopy showed the intermediates of the LDA-promoted reactions to be radical anions of the product benzocycloalkanes. This supported an SRN1-type chain mechanism involving initial production of aryl radicals connected to azaenolate ions via the spacer groups. Intramolecular radical to carbanion coupling then generated ring-closed benzocycloalkane radical anions that transferred an electron to more precursor. Diastereoselective radical to carbanion cyclo-coupling reactions were carried out with 2-bromophenylpropyl precursors containing chiral 2-oxazolines. The diastereoselectivity achievable was modest, but the product diastereoisomeric Indane derivatives were easily separable by chromatography.     

Photolysis of 2-phenylethyl and 4-phenyl-1-butyl halides in alcoholic solvents

Photolysis of 2-phenylethyl bromide in the lower alcohols gave the corresponding carbinols and ethers as the main products. With 2-phenylethyl iodide, the products were almost exclusively of the latter type, while 4-phenyl-1-butyl halides gave n-butylbenzene, 4-phenyl-1-butene and tetralin.It is shown chac each of these produtes may be assigned to an ionic or radical pathway and that both the nature of the solvent and the structure of the substrate affect the course of photolysis. There is a substrate dependent preference for specific reactions along pathways of both the radical and ionic types. The variations in product composition and distribution are rationalized in terms of the relative efficiencies furnished in these pathways for the relaxation of high energy intermediates produced in the initial stages of photolysis. Intervention by the phenyl group is more pronounced in the case of 2-phenylethyl halides than In the case of the higher homologues and more effective in the ionic pathway.     

4(3H)-Quinazolinones containing heterocyclic group in position 3

The corresponding 2,3-substituted 4(3H)-quinazolinones were obtained in the reactions of 2-methyl- and 2-phenyl-4-oxo-3,1-benzoxazines with 1-amino-1,2,4-triazole, 4-amino-2,3-dimethyl-1-phenyl-5-pyrazolone, 2-amino-5-ethyl-1,3,4-thiadiazole, 3-amino-6,6-dimethyl-4-oxo-4,5,6,7-tetrahydroindazole, 1-amino-3-cyano-4,6-dimethyl-2-pyridone, and 1-amino-3-cyano-6-phenyl-4-trifluoromethyl-2-pyridone. The formation of N-benzolyanthranilamides in the reactions of 2-phenyl-4-oxo-3,1-benzoxazine with 2-amino-5-ethyl-1,3,4-thiadiazole and 1-amino-3-cyano-6-phenyl-4-trifluoromethyl-2-pyridones was exceptional. The structures of two of the products have been confirmed by X-ray crystallography.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 936–943, July, 2000.     

含噻吩基的三硅烷在辐照下的反应

通过类似的格氏反应合成了2-苯基-2-呋喃基六甲基三硅烷和2-苯基-2-噻吩基六甲基三硅烷.前者在2,3-二甲基-1,3-丁二烯存在时的光解导致正常的硅烯-烯烃加成和硅烯C-H插入反应.而噻吩基三硅烷在甲醇一环乙烷体系中被光解,产生自由基反应,我们怀疑噻吩中的硫原子对硅烷自由基有强烈的稳定作用.通过对典型的自由基反应产品的鉴定以及它的用自由基猝灭剂的猝灭产品的电子自旋共振谱也支持了这一结果.     

Divergent oxidative rearrangements in solution and in a zeolite: distal vs proximal bond cleavage of methylenecyclopropanes

Irradiation of 9,10-dicyanoanthracene (DCA) or p-chloranil in the presence of E-1-benzylidene-2-phenylcyclopropane (E-5) in CH(2)Cl(2) causes E-5 to undergo methylenecyclopropane rearrangement. An adduct, Z-7, between DCA and 5 firmly supports the involvement of a bifunctional trimethylenemethane radical cation. In contrast, incorporation of E-5 into HZSM-5 produces trans,trans-1,4-diphenyl-1,3-butadiene radical cation sequestered in the HZSM-5 interior, tt-8(.+)@HZSM-5, identified by ESR and diffuse reflectance spectroscopy. In addition, low yields of tt-8, its cis,trans-isomer (ct-8), and 1-phenyl-1,2-dihydronaphthalene (9) were isolated from the supernatant solution. The sharp contrast between the photoinduced electron-transfer reaction with photosensitizers in solution and the spontaneous reaction with redox-active acidic zeolite offers the prospect of further zeolite-induced regiodivergent reactions in a range of additional substrates.     

Reaction of α-keto hydrazonyl bromide with carbanions of some active methylene compounds

Treatment of 1-phenyl-2-bromo-2-arylhydrazonoethanone (VII) with sodium etiolates of 2,4-pentanedione, 1-phenyl-1,3-butanedione, dibenzoylmethane, ethyl benzoylacetate, acetoaceta-nilide, and of benzoylacetanilide in ethanol afforded the substituted pyrazoles, VIII-XIII, respectively. The results show that VII, unlike 1-phenyl-2-bromo-2-hydroximinoethanone (V), is not easily deprotonated by carbanions; and that its reactions with β-diketones, β-keto esters, and β-keto amides follow one and the same mechanism. The structures of the products (VIII-XIII) were inferred from their elemental analyses and spectral data.     

One-Pot synthesis of N-heterocyclic compounds from cyclopropenethione derivatives

The one-pot reaction of 2-tert-butylthio-3-phenylcyclopropenethione (1a) and its 3-(2-thienyl) derivative (1b) with lithium pyrrolidinide at -70 degrees C, followed by methylation with methyl iodide, gives 6-methylthio-5-phenyl-2,3-dihydro-1H-pyrrolizine (2a) and its 5-(2-thienyl) derivative (2b), respectively. The reaction of 2-tert-butylthio-3-(pyrrolidin-1-yl)cyclopropenethione (1c) with phenyllithium gives also 2a in a high yield under similar conditions, and the reactions of 1a with N-lithium salts of 3-pyrroline, hexamethyleneimine, indoline, and carbazole, piperidine-potassium tert-butoxide mixture, and phenyllithium give 6-methylthio-5-phenyl-3H-pyrrolizine (3), 2-methylthio-3-phenyl-6,7, 8,9-tetrahydro-5H-pyrrolo[1,2-a]azepine (5), 6-tert-butylthio-5-methylthio-4-phenyl-1,2-dihydro-6H-pyrrolo[3,2, 1-ij]quinoline (6), 4-tert-butylthio-5-methylthio-6-phenyl-4H-pyrido[3,2,1-jk]carbazole (7), 2-methylthio-3-phenyl-5,6,7,8-tetrahydroindolizine (4), and 1-tert-butylthio-2-methylthio-3-phenylindene (9), respectively. The structures of 2a and 3 were determined by X-ray analyses of their tricarbonylchromium complexes.     

Studies on Reactions of Cyclic Oxalyl Compounds with Hydrazines or Hydrazones. 2. Synthesis and Reactions of 4-Benzoyl-1-(4-nitrophenyl)-5-phenyl-1H-pyrazole-3-carboxylic Acid

4-Benzoyl-1-(4-nitrophenyl)-5-phenyl-1H-pyrazole-3-carboxylic acid, obtained from the corresponding furan-2,3-dione and N-benzylidene-N'-(4-nitrophenyl)hydrazine, was converted via reactions of its acid chloride with various alcohols or N-nucleophiles into the corresponding ester or amide derivatives. The nitrile of the starting acid and 1-(4-aminophenyl)-4-benzoyl-5-phenyl-1H-pyrazole-3-carboxylic acid were also obtained. While cyclocondensation reactions of the two acids and the nitrile mentioned with hydrazines lead to pyrazolo[3,4-d]pyridazine derivatives, the reaction of starting acid with 2-hydrazinopyridine provided the hydrazonopyrazole acid derivative.     

Ion/molecule reactions performed in a miniature cylindrical ion trap mass spectrometer

A recently constructed miniature mass spectrometer, based on a cylindrical ion trap (CIT) mass analyzer, is used to perform ion/molecule reactions in order to improve selectivity for in situ analysis of explosives and chemical warfare agent simulants. Six different reactions are explored, including several of the Eberlin reaction type (M. N. Eberlin and R. G. Cooks, Org. Mass Spectrom., 1993, 28, 679-687) as well as novel gas-phase Meerwein reactions. The reactions include (1) Eberlin transacetalization of the benzoyl, 2,2-dimethyloximinium, and 2,2-dimethylthiooximinium cations with 2,2-dimethyl-1,3-dioxolane to form 2-phenyl-1,3-dioxolanylium cations, 2,2-dimethylamine-1,3-dioxolanylium cations and the 2,2-dimethylamin-1,3-oxathiolanylium cations, respectively; (2) Eberlin reaction of the phosphonium ion CH3P(O)OCH3+, formed from the chemical warfare agent simulant dimethyl methylphosphonate (DMMP), with 1,4-dioxane to yield the 1,3,2-dioxaphospholanium ion, a new characteristic reaction for phosphate ester detection; (3) the novel Meerwein reaction of the ion CH3P(O)OCH3+ with propylene sulfide forming 1,3,2-oxathionylphospholanium ion; (4) the Meerwein reaction of the benzoyl cation with propylene oxide and propylene sulfide to form 4-methyl-2-phenyl-1,3-dioxolane and its thio analog, respectively; (5) ketalization of the benzoyl cation with ethylene glycol to form the 2-phenyl-1,3-dioxolanylium cation; (6) addition/NO2 elimination involving benzonitrile radical cation in reaction with nitrobenzene to form an arylated nitrile, a diagnostic reaction for explosives detection and (7) simple methanol addition to the C7H7+ ion, formed by NO2 loss from the molecular ion of p-nitrotoluene to form an intact adduct. Evidence is provided that these reactions occur to give the products described and their potential analytical utility is discussed.     

SYNTHESIS AND FREE RADICAL POLYMERIZATION OF 2-OXO-3-METHYLEN E-5-PHENYL-1,4-DIOXAN

The novel cyclic monomer, 2-oxo-3-methylene-5-phenyl-1,4-dioxan, was synthesized by a set of reactions. Several intermediates were prepared and characterized in order to determine the monomer structure. The presence of chiral centers in the intermediates and resulting monomer makes it complicated to separate , purify and characterize them. It is a very reactive monomer which will polymerize even at room temperature if expose to moisture and air. This monomer can undergo essentially quantitative flee radical ring opening polymerization. The driving force for ring opening is the formation of new carbonyl group and benzylic radical. The monomer and polymer structure were established by IR, ~1H NMR, ~(13)C NMR and elemental analysis or high resolution mass spectrum. The molecular weight of the resulting polymer was estimated by viscosity determination.     

New method for the synthesis of N-tert-alkoxyarylaminyl radicals

The reactions of 2,4-diaryl-6-tert-butylnitrosobenzenes with 2,2'-azobis[2-(methoxycarbonyl)propane] (5a), 2,2'-azobis(2-cyano-4-methylpentane) (5b), and 2,2'-azobis(2-cyano-4-methyl-4-methoxypentane) (5c) in refluxing benzene gave stable N-tert-alkoxy-2,4-diaryl-6-tert-butylphenylaminyls, which were successfully isolated as radical crystals in 13-52% yields after column chromatography. The radical yields depended on the reaction time and the molar ratio of azo compounds to nitroso compounds. In the same manner, acetyl- and cyano-group-carrying N-tert-alkoxyarylaminyls were generated by the reaction of 2-phenyl-4-(4-acetylphenyl)-6-tert-butylnitrosobenzene and 2-phenyl-4-(4-cyanophenyl)-6-tert-butylnitrosobenzene with 5a and 5b, and they were isolated as radical crystals. X-ray crystallographic analyses were performed for two radicals, and their molecular structures were discussed in detail. The magnetic properties were measured for the two isolated radicals with SQUID in the temperature range 1.8-300 K. One radical showed a weak ferromagnetic interaction (theta = 0.2 K) between the radicals, and the other showed a weak antiferromagnetic interaction (theta = -3.8 K). The ferromagnetic interaction was analyzed based on the X-ray crystallographic structure.     

The features of the kinetics of radical reactions of quinone imines with 2-mercaptobenzothiazole

Kinetics of the reactions of N-phenyl-1,4-benzoquinone monoimine and N,N′-diphenyl-1,4-benzoquinone diimine with 2-mercaptobenzothiazole in chlorobenzene at T = 343 K has been studied by using kinetical spectrophotometry method (periodic spectral measurements and/or monitoring the wavelengths of the absorption band of quinone imines in the visible region). Two general features of the reactions, namely, radical mechanism and the existence of two steps were found. Kinetic features depend on the structure of a quinone imine. A reaction between N,N′-diphenyl-1,4-benzoquinone diimine and 2-mercaptobenzothiazole at first (initial) steps proceeds in an autoinhibition mode and has two independent channels, one of which being radical-chain. The addition of an initiator strongly accelerates the reaction only at the initial step, on completion of which the reaction rate decreases significantly and do not depend on the presence of the initiator. This testifies to the proceeding of the reaction by a non-chain mechanism subsequently to the initial step. The interaction involving N-phenyl-1,4-benzoquinone monoimine proceeds by a radical non-chain mechanism from the very beginning up to the end, and at the initial steps it proceeds in the autoaccelerating mode. The initiator has no influence on the reaction rate. For the process of the interaction of N,N′-diphenyl-1,4-benzoquinone monoimine and 2-mercaptobenzothiazole in the presence of 4-hydroxydiphenylamine, a radical mechanism was proposed, that serves to describe the kinetic features of the reaction and to obtain a quantitative estimation of some of its kinetic parameters.     

Reactions of polyhalomethanes with olefins catalyzed by copper complexes with aromatic amino alcohols

Copper complexes with amino alcohols structurally similar to ephedrin (1-phenyl-3-(N-methylamino)propan-1-ol and 1-phenyl-2-(N-methylamino)ethanol) are catalytically very active in the free-radical addition of CCl₄ and CBr₄ to linear alk-1-enes. These amino alcohols themselves are initiators of radical addition reactions, and, in the reaction with CBr₄, they are more active than the metal complexes. In the presence of the amino alcohols, as distinct from classical radical initiators, the reaction is highly selective and affords an addition product. An analysis of kinetic equations and the data obtained for the reaction involving CHCl₃ suggest that the amino alcohols and the corresponding metal complexes are involved in different ways in the addition of CCl₄ and CBr₄ to linear alk-1-enes.     

Dediazoniation of arenediazonium salts with trivalent-phosphorus compounds. Tool for examination of the reactivity of phosphorus-centered radicals

Trialkyl phosphites ( 1 ), dialkyl phenylphosphinites ( 2 ), and alkyl diphenylphosphonites ( 3 ) as well as 2-phenyl-1,3,2-dioxaphospholan ( 4b ) and 2-phenyl-1,3,2-dioxaphosphorinan ( 4b ) give rise to dediazoniation of arenediazonium salt ( 5 ) in an alcoholic solvent under an argon atmosphere at 20°C. The reaction proceeds via a radical-chain mechanism initiated by single-electron transfer (SET) from the trivalent-phosphorus compounds to 5 , as a result of which, an aryl radical Ar⋅ and a cation radical 15 are generated from the former and the latter, respectively. The aryl radical Ar⋅ participates in this chain process abstracting a hydrogen from the solvent alcohol, yielding the corresponding arene ArH. The cation radical 15 undergoes both an ionic reaction with the solvent alcohol and a radical coupling with Ar⋅, giving the phosphoranyl radical 16 and the phosphonium ion 17 , respectively, as intermediates. The phosphoranyl intermediate 16 decomposes through either the SET process to 5 or by β-scission, yielding the oxidation product (phosphate, phosphonate, or phosphinate from 1 , 2 , or 3 , respectively, or phosphonates from 4 ). The phosphonium intermediate 17 affords the arylated product (phosphonate, phosphinate, or phosphine oxide from 1 , 2 , 3 , respectively, or the phosphinate from 4 ). Among the trivalent-phosphorus compounds tested, 1 gives the arylated product in the highest yield. This observation, together with the literature data of ESR for structurally related phosphoranyl radicals, indicates that the radical coupling of 15 with Ar⋅ is facilitated by the high spin density on its central phosphorus atom.     

Magnetic resonance studies of imidazoline nitroxides and their photochemical transformations

ESR, ¹H and ¹³C NMR, ENDOR and TRIPLE resonance have been employed to study photochemical reactions of 2,2,5,5-tetramethyl-4-phenyl-3-imidazoline-3-oxide-1-oxyl and to determine the electronic structures of the initial and final radicals. The light-induced isomerization of a phenyl nitron group to an oxaziridine group has been shown to proceed without involving the radical centre.     

Synthesis and potentiometric analysis of organophosphorus metal complexones and complexonates based on 2-aminothiazole derivatives

Synthesis conditions of 4-phenyl-2-amidothiazolyl acetate and 2-thiourido-4-diethylphosphothiazole were developed, and the complexation capacity of these compounds in formation of mixed-ligand complexes was studied. The optimal conditions and thermodynamic parameters of the complexation process were determined. The potentiometric method was used to find thermodynamic parameters of the reactions of mixed-ligand complexation with copper(II) and lead(II) ions, the composition of the complexes being formed on the basis of 4-phenyl-2-aminothiazole and its phosphorylated derivatives was determined.     

Mass spectrometry for investigations of gas-phase radical cation chemistry : The two step cycloaddition of the benzene radical cation and 1,3-butadiene

Mass spectrometric techniques are now used extensively for the study of gas-phase radical cation chemistry. The generation and structural properties, the unimolecular and bimolecular chemistry of some representative radical cation systems, and the methods of study are reviewed. The structure of the ionmolecule adduct produced in the reaction of the benzene radical cation and neutral 1,3-butadiene was investigated by collisionally stabilizing the adduct and then acquiring its collision-activated decomposition spectrum. The CAD spectrum of the adduct changes dramatically as a function of the degree of collisional stabilization. This observation is interpreted in terms of two distinct structures for the adduct. The species that is stabilized at 0.7 Torr has a CAD spectrum similar to the 2-phenyl-2-butene radical cation. The second structure, stabilized at 0.1 Torr, has a CAD similar to that of 1-methylindan. The results of these experiments are interpreted in terms of a two-step cycloaddition mechanism for the formation of the 1-methylindan radical cation.     

2－氯／2－甲磺酰基－5－（2－苯基－4－喹啉基）－1，3，4－噁二唑化合物的合成及其亲核取代的研究

借处理２－羟基－５－（２－苯基－４－喹啉基）－１，３，二唑同ＰＣｌ＿５／ＰＯＣｌ＿３之间的反应合成了２－氯－５－（２－苯基－４－喹啉基）－１，３，４－二唑（３）和通过２－基－５－（２－苯基－４－喹啉基）－１，３，４－二唑的甲基化，然后氧化制得２－甲磺酰基－５－（２－苯基－４－喹啉基）－１，３，４－二唑（６）．并分别研究了３和６同胺、叠氮及肼的反应，得到２，５－二取代的二唑新衍生物．初步观察了部分化合物的抗菌活性．