Mass spectra of new heterocycles: XV. Fragmentation of 1-substituted 3-alkoxy-2-(propargylsulfanyl)- and 3-alkoxy-2-(allenylsulfanyl)-1<Emphasis Type="Italic">H</Emphasis>-pyrroles under electron impact

The electron impact mass spectra of 1-R-substituted 3-alkoxy-2-(propargylsulfanyl)- and 3-alkoxy-2-(allenylsulfanyl)-1H-pyrroles (R = Me, i-Pr, s-Bu, Ph) have been studied for the first time. These compounds give rise to stable molecular ions whose primary fragmentation follows three competing pathways: cleavage of the C–O bonds with expulsion of alkyl radical, cleavage of the C–S bonds with formation of [M–C₃H₃]⁺ ions, and cleavage of the C–N bonds with synchronous hydrogen transfer to give odd-electron [M–C_nH_2n]+ · ion. The main fragmentation pathway of 2-(propargylsulfanyl) derivatives is cleavage of the C–S bond with formation of [M–C₃H₃]⁺ ion.     

Mass spectra of new heterocycles: XI. Fragmentation of 5-(methylsulfanyl)-1-[2-(vinyloxy)ethyl]-1H-pyrrol-2-amines under electron impact and chemical ionization

Fragmentation patterns of the molecular ions of 5-(methylsulfanyl)-1-[2-(vinyloxy)ethyl]-1H-pyrrol- 2-amines generated by electron impact (70 eV) and chemical ionization (methane as reagent gas) were studied for the first time. The electron impact mass spectra of all the examined compounds showed abundant molecular ions whose subsequent fragmentation followed three main pathways: elimination of EtS radical, elimination of methyl radical from the MeS group, and cleavage of the C-N and/or C-C bonds which is accompanied by rearrangement processes. Further decomposition of the [M - EtS]⁺ ion is determined by the structure of the amino group. The chemical ionization mass spectra displayed strong molecular and [M + H]⁺ ion peaks together with representative series of fragment ion peaks. Unlike electron impact, the main decomposition pathway under chemical ionization is elimination of methylsulfanyl radical from the [M + H]⁺ ion to give abundant [M + H — MeS]⁺ ion.     

Synthesis of 3-aryl(hetaryl)-1,2,3-diazaphospholines

A reaction of cyclohexanone phenylhydrazone with (het)aryldihalogenophosphines has been studied. As shown, cyclohexanone phenylhydrazone reacts with phenyldibromophosphine and 5-methyl-2-furyldibromophosphine to provide the corresponding 1,2,3-diazaphospholines in high yields. The diazaphospholines thus obtained have been derivatized. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:81–83, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20074     

Plant coumarins: VIII. Suzuki reaction in the synthesis of 3-aryl(hetaryl)furocoumarins

Suzuki cross coupling of oreoselone trifluoromethanesulfonate with substituted phenyl- and hetarylboronic acids in the presence of palladium complexes with uni- and bidentate ligands gave the corresponding 3-substituted furocoumarins.     

Mass spectra of new heterocycles: XIV. Investigation of 2-(alkyl- and propargylsulfanyl)-3-(ferrocenylmethoxy)pyrroles by electron ionization and laser desorption/ionization

By mass spectrometry methods applying electron ionization (70 eV) and laser desorption/ionization (NALDI, MALDI) 1-(alkyl-, cycloalkyl-, vinyloxyethyl-, and aryl)substituted 2-(alkyl- and propargylsulfanyl)-3-(ferrocenylmethoxy)pyrroles were studied and characterized. At the electron ionization the peak of the molecular ion possesses very low intensity. The main fraction ions are the ferrocenylmethyl ion (the most abundant peak) and its decomposition ions. Under the NALDI conditions molecular ions and protonated molecules [M + H]⁺ are generated. The general fragmentation rules in the field-free region are determined. By an example of 1-phenyl derivative of pyrrole the MALDI procedure was also demonstrated to be suitable for investigation of 2-(alkylsulfanyl)-3-(ferrocenylmethoxy)pyrroles.     

Mass spectra of stereoisomeric cis- and trans-2-alkyl-3-aryl(hetaryl)-4-(methoxycarbonyl)-3,4-dihydro-1h-isoquinol-1-ones and 1,2,3,4-tetrahydroisoquinolines

The molecular ions of the trans isomers of the investigated compounds are more stable than those of the cis isomers. Their principal fragmentation pathways involve retrodiene fragmentation of the molecular ions, which proceeds with greater probability in the case of the cis isomers, or loss of substituents from the 4 or 3 position. The latter process is characteristic only for tetrahydroisoquinoline derivatives, is not observed for 3,4-dihydro-1H-isoquinol-1-one derivatives, and proceeds more readily in the case of the trans isomers.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1395–1397, October, 1980.     

Mass spectra of new heterocycles: VII. Main fragmentation channels of 2-(methylsulfanyl)-4,5-dihydro-3H-azepines under electronic ionization

Russian Journal of Organic Chemistry - Mass spectra of 3,7-di- and 3,6,7-trisubstituted 2-(methylsulfanyl)-4,5-dihydro-3H-azepines were investigated for the first time. The fragmentation of...     

New derivatives of 3-aminoindole. Synthesis of 2-aryl(hetaryl)-3-(3,5-dimethyl-1-pyrazolyl)indoles

The interaction of arylhydrazines with ù-(3,5-dimethyl-1-pyrazolyl)acetophenones and acetyl(2-thiophene) leads to arylhydrazones, which are converted by Fischer cyclization into 2-aryl(thienyl)-3-(3,3-dimethyl-1-pyrazolyl)indoles with substituents in positions 1, 5, and 7.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1662–1669, November, 2004.     

Synthesis of 7-acetyl-8-aryl(hetaryl)- 6-hydroxy-1,6-dimethyl-3-selenoxo-2,3,5,6,7,8-hexahydroiso-quinoline-4-carbonitriles by the condensation of 2,4-diacetyl-3-aryl(hetaryl)- 5-hydroxy-5-methyl-cyclohexanones with cyanoselenoacetamide

7-Acetyl-8-aryl(hetaryl)-6-hydroxy-1,6-dimethyl-3-selenoxo-2,3,5,6,7,8-hexahydroisoquinoline-4-carbo- nitriles have been obtained by the condensation of 2,4-diacetyl-3-aryl(hetaryl)-5-hydroxy-5-methyl-cyclohexanones with cyanoselenoacetamide.     

Hydrazides of 4-aryl(hetaryl)-2-oxopyrrolidine-3-carboxylic acids: Synthesis and structure

Proceeding from reactions of methyl 4-aryl(hetaryl)-2-oxopyrrolidine-3-caroxylates with hydrazine and phenylhydrazine a series of hydrazides of the corresponding 2-oxopyrrolidine-3-carboxylic acids was obtained combining in the molecule a lactam ring and carbohydrazide groups. Phenylhydrazides of 2-oxopyrrolidine-3-carboxylic acids possess the Z-configuration.     

Nitropyridines: VI. Synthesis of 2-aryl(hetaryl)- and 2,3-polymethylene-5-nitropyridines

Previously unknown 2-aryl-, 2-hetaryl-, and 2-cyclopropyl-5-nitropyridines and 2,3-polymethylene-5-nitropyridines were synthesized by reactions of 1-methyl-3,5-dinitropyridin-2(1H)-one with various cyclic and acyclic ketones in the presence of ammonia.     

Mass spectra of new groups of functionalized heterocycles. 4. 1-Alkyl-2-(alkylthio)pyrroles

The electron impact-induced fragmentation of 1-alkyl-2-(alkylthio)pyrroles is accompanied by rearrangements of the molecular and fragment ions with ring expansion.     

Synthesis and Structure of (2E)-3-Aryl(hetaryl)-2-[5-bromo-4-aryl(hetaryl)-1,3-thiazol-2-yl]acrylonitriles

Russian Journal of General Chemistry - Bromination of (2E)-3-aryl(hetaryl)-2-[4-aryl(hetaryl)-1,3-thiazol-2-yl]acrylonitriles proceeds regioselectively at the C5 atom of the thiazole ring with the...     

Synthesis and structure of amides of 4-aryl(hetaryl)-2-pyrrolidone-3-carboxylic acids

Amides of 4-aryl(hetaryl)-2-pyrrolidone-3-carboxylic acids have been prepared via ammonolysis of the corresponding esters of pyrrolidone carboxylic acids. The products structure has been characterized by means of IR, ¹H NMR, ¹H–¹³C HMQC, and HMBC spectroscopy.     

Efficient synthesis of 3-aryl(hetaryl)-1,5,3-dioxazepanes involving catalysts containing Sm and Co

Efficient synthetic procedure was developed for 3-aryl(hetaryl)-1,5,3-dioxazepanes consisting in the transamination of 3-tert-butyl-1,5,3-dioxazepane with arylamines and also by the reaction of 1,2-ethanediol with N,N-bis(methoxymethyl)aryl(hetaryl)amines in the presence of catalytic amounts of Sm and Co compounds.     

Steric structure of alkyl 2-aryl(hetaryl)hydrazono-3-fluoroalkyl-3-oxopropionates

Steric structure of fluorinated 2-arylhydrazono-3-oxo esters was studied by ¹H, ¹⁹F, and ¹³C NMR spectroscopy and X-ray analysis. It was found that these compounds in the crystalline state and in solutions in acetone-d ₆, DMSO-d ₆, and CDCl₃ exist as Z isomers with the ester fragment involved in intramolecular hydrogen bond with the hydrazone NH proton. Exceptions are alkyl 2-arylhydrazono-4,4-difluoro-3-oxobutanoates which exist in acetone-d ₆ as mixtures of Z and E isomers, the former prevailing. Unlike fluorinated analogs, ethyl 2-(4-methylphenyl)hydrazono-3-oxobutanoate in crystal has the structure of E isomer in which intramolecular hydrogen bond is formed between the NH proton and acetyl carbonyl group. The same compound in acetone-d ₆, DMSO-d ₆, and CDCl₃ gives rise to a mixture of Z and E isomers, the latter prevailing.     

A new synthesis of 6-(alkyl)amino-3-aryl(alkyl)-1,2,4,5-tetrazines

A new method for the preparation of 6-(alkyl)amino-3-aryl(alkyl)-1,2,4,5-tetrazines is described. Dissolving 3-aryl(alkyl)-1,2,4,5-tetrazines in liquid ammonia or a primary aliphatic amine at ?35° to ?40°, followed by addition of potassium permanganate gives the title compounds in reasonable to excellent yields.     

Mass spectra of new heterocycles: XVI. Electron impact study of alkyl 5-aminothiophene-2-carboxylates

Electron impact mass spectra of alkyl 4-alkoxy-5-amino-3-methylthiophene-2-carboxylates were studied for the first time. These compounds, except for 4-(1-ethoxyethoxy) and 4-(ferrocenylmethoxy) derivatives, give rise to a stable molecular ion whose decomposition follows three pathways. The main fragmentation pathway of the molecular ion is elimination of alkyl radical from the 4-alkoxy group, the second pathway involves expulsion of alkoxy group from the ester moiety, and the third pathway is decomposition of the thiophene ring. The molecular ions of 4-(1-ethoxyethoxy)thiophenes decompose mainly via elimination of ethyl vinyl ether molecule with formation of [M–VinOEt]⁺ · odd-electron ion, and fragmentation of the latter follows general pathways. In the mass spectra of 4-(ferrocenylmethoxy)thiophenes the most abundant are ferrocenylmethyl ion with m/z 199 (I _rel 100%) and fragment ions derived therefrom.     

Fragmentation of 2- and 4-(2-furyl) pyridines under the influence of electron impact

The dissociative ionization of 12 compounds of the 2- and 4-(2-furyl)pyridine series that contain methyl, ethyl, and n-propyl groups in various positions of the pyridine ring was investigated. It was established that the intensity of the [M — H]⁺ ion peak depends only slightly on the mutual orientation of the alkyl groups and the furyl grouping, while the probability of cleavage of the furan ring with ejection of CO and HCO particles is very sensitive to these structural factors. Cleavage of the pyridine ring leads to the development of [M — HCN]⁺ and [FuCN]⁺ ions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 769–774, June, 1982.     

Mass spectra of new heterocycles: IX. Main fragmentaion laws of 7-methyl-2-(methylsulfanyl)-3-(1-ethoxyethoxy)-4,5-dihydro-3<Emphasis Type="Italic">H</Emphasis>-azepine and its structural isomers (2,3-dihydropyridine,pyrrole, thiophene) under electron impact

Mass spectra were investigated for the first time of four structural isomers of heterocycles, formerly inavailable 7-methyl-2-(methylsulfanyl)-3-(1-ethoxyethoxy)-4,5-dihydro-3H-azepine, 2,2-dimethyl-6-(methylsulfanyl)-5-(1-ethoxyethoxy)-2,3-dihydropyridine, 1-isopropyl-2-(methylsulfanyl)-3-(1-ethoxyethoxy)pyrrole, and N-isopropyl-N-methyl-3-(1-ethoxyethoxy)-2-thiophenamine prepared from a single linear precursor, adduct of α-lithiated 1-(1-ethoxyethoxy)allene and isopropyl isothiocyanate. All compounds formed a molecular ion (I _rel 1–6%) whose primary fragmentation at the electron impact (70 eV) occurs in two principal directions related to the cleavage of the C-O bonds in the 1-ethoxyethoxy-substituent: with a simple rupture of the bonds C-OEt and C-O(heterocycle) and with the elimination of an ethoxyethene molecule. In the spectra of 4,5-dihydro-3H-azepine and 2,3-dihydropyridine the first fragmentation channel of [M]^+· dominates. The second direction prevailes at the fragmentation of pyrrole and thiophene molecular ions leading to an odd-electrons ion with m/z 171. Further fragmentation of this ion is characteristic of each isomer and resulted in the formation of diagnostic ions providing a possibility of identification of these isomers by mass spectrometry.