Synthesis and attempted polymerization of N-arylmaleimides substituted with allylamino or cyclopropylamino groups at 2-position

Several N-substituted chloromaleimides were prepared by dehydrating the corresponding chloromaleamic acids. Treatment of chloromaleimides with allylamine or cyclopropylamine produced N-aryl-2-(allylamino)maleimides and N-aryl-2-(cyclopropylamino)maleimides, respectively. Neither the N-substituted chloromaleimides nor the N-aryl-2-(allylamino) or N-aryl-2-(cyclopropylamino)maleimides polymerized free radically or anionically. The difficulty of achieving good pi-pi overlap and stiric effects at the propagation step prevented the cyclopolymerization of the prepared 1,5-dienes.     

Hydrogen migration in the electron impact induced retro diels-alder fragmentation of N-aryl-4H-5,7a-epoxyisoindolines

The electron impact induced fragmentations of the C-5 unsubstituted and 5-methyl N-aryl-4H-5,7a-epoxyisoindolines (where aryl is pheny, p-tolyl, p-methoxyphenyl, o-methoxyphenyl and p-chlorophenyl) were investigated. The fragmentation patterns deduced were supported by exact mass measurements of prominent ions and by deuterium labelling. The retro Diels-Alder fragmentation turned out to be a predominant process in all the compounds investigated. In the mass spectra of the 5-methyl N-aryl-4H-5,7a-epoxyisoindolines hydrogen migration preceding fragmentation occurred. From the mass spectrum of the specifically deuterated compound it was concluded that the transferred hydrogen originates exclusively from the 5-methyl group.     

Electron-impact fragmentation of N-substituted 2-aminobenzoxazoles and 2-aminobenzothiazoles

The mass spectra of twenty-eight N-substituted 2-aminobenzoxazoles and 2-aminobenzothiazoles have been recorded and the identity of various ions in the mass spectra have been established by high resolution measurement. The molecular compound of series, benzoxazole, undergoes loss of hydrogen cyanide and carbon monoxide from the molecular ion as the most important decomposition pathways. The mass spectra of N-substituted benzothiazoles showed a similar fragmentation as that of N-substituted benzoxazoles.     

Mass spectrometry of 2-substituted-1-keto-3-aryl-5H-imidazo-(1,5-a)-pyrroles derived from Schiff bases of N-terminal prolyl peptides

We have been able to extend the use of Schiff base derivatives in peptide sequencing to N-terminal prolyl peptides. Earlier studies from this laboratory revealed that certain aromatic Schiff bases of peptide esters gave electron-impact mass spectra with relatively intense molecular, sequence and internal fragment ions. We observed that the reaction of N-terminal prolyl peptide esters with 4-dimethylaminonaphthaldehyde, p-dimethylaminobenzaldehyde and 2-pyridinecarboxaldehyde gave cyclization products which were found to be 2-substituted-1-keto-3-aryl-5H-imidazo-[1,5-a]-pyrrole derivatives. The molecular ion and many of the expected cleavages were prominent in the mass spectra. Deuterium labeling at the α-carbon, amide nitrogen, or other exchangeable positions has been used in assigning the structure. It was also confirmed by the fragmentation pattern of the products derived by permethylation of the peptide derivative with tetramethylammonium hydroxide. Comparable cleavage patterns were seen among the N-terminal prolyl peptides examined. Proline amide gave the corresponding cyclized product. With the inclusion of N-terminal prolyl peptides in the list of peptides that we have examined, we may now prepare volatile derivatives of peptides containing any of the protein amino acids in two steps: esterification and treatment with the appropriate aromatic aldehyde.     

Chemical ionization and electron impact mass spectra of alicyclic substituted 2-aryl-1,3-dithianes

The methane and isobutane chemical ionization mass spectra of alicyclic substituted 2-aryl-1,3-dithianes were examined by gas chromatography mass spectrometry. The protonated molecular ion was found to be of low abundance in the methane spectra, while a protonated cyclic sulfide cation (m/z 107) appeared as the base peak. A protonated molecular ion was the base peak when isobutane was used as the reagent gas. Electron impact mass spectra displayed weak molecular ions and were characterized by the m/z 106 fragment.     

1-Alkyl-4-aryl-3,4-dihydro-2(1H)-quinazolinones and thiones. Synthesis and 1H-NMR spectra

A series of 1-alkyl-4-aryl-3,4-dihydro-2(1H)-quinazolinones and thiones were prepared by a modification of the Pictet-Spengler reaction that involves treatment of an N-alkyl-N-arylurea or thiourea with an aryl aldehyde in the presence of methanesulfonic acid. The ¹H-nmr spectra of several of these compounds gave rise to unusual OCH₂O and isopropyl signals.     

Synthesis and properties of 1-aryl-2-alkyl-1,4,5,6-tetrahydropyrimidines

A general method is described for the synthesis of 1-aryl-2-alkyl-1,4,5,6-tetrahydropyrimidines 1 , by cyclization of N-acyl-N′-aryltrimethylenediamines 2 with trimethylsilyl polyphosphate. Precursors 2 were obtained by aminolysis of the corresponding N-(3-bromopropyl)amides 3. The ¹H nmr spectra of tetrahydropyrimidines 1 are analyzed, discussing the influence of substituents in positions 1 and 2 of the heterocyclic ring. Alkaline hydrolysis of compounds 1 , which originates exclusively N-acyl-N′-aryltrimethylenediamines 2 , through an intermediate carbinolamine, was also studied. Cleavage of such an intermediate is discussed in the light of the stereoelectronic control theory. Reduction of compounds 1 with borane, leads regiospecifically to N-alkyl-N′-aryltrimethylenediamines 6.     

Reactions of 2-amino-, 2-alkylamino-, and 2-piperidino-1-azaazulenes with aryl and chlorosulfonyl isocyanates

Reaction of 2-amino-1-azaazulene with phenyl isocyanate gave 3-phenyl-2H-3,4-dihydro-1,3,4a-triazabenz[5,4-a]azulene-2,4-dione. Reactions of 2-alkylamino-1-azaazulenes with aryl isocyanates gave 2-(N-ethyl-N′-arylureido)-1-azaazulenes initially, which rearranged to N-aryl-2-alkylamino-1-azaazulene-3-carboxamides and successive reaction with another molar amount of aryl isocyanate furnished uracil-fuzed 1-azaazulenes. Reaction of 2-piperidino-1-azaazulene with aryl isocyanate gave N-aryl-2-piperidino-1-azaazulene-3-carboxamide. Reaction of 2-(substituted amino)-1-azaazulenes with chlorosulfonyl isocyanate gave 3-cyano- and 3-chloro-2-(substituted amino)-1-azaazulenes.     

A novel reaction of (2a7-trinito-9H-fluoren-9-ylidene)-propanedinitrile with N-arylisoindolines

N-Arylisoindolines 1a-c reacted with (2,4, 7-trinitro-9H-fluoren-9-ylidene)propanedinitrile ( A ) in pyridine with admission of air via a net α-H-atom abstraction and formation of [3-(2-aryl-3-arylimino-2,3-dihydro- 1H-isoindol-1-ylidene)-2-aryl-2,3-dihydro-1H-isoindol-1-ylidene]propanedinitriles 2a-c , N-[2-aryl-3-(2-aryl-3-arylimino-2,3-dihydro-1H-isoindolyl-1-idene)-2,3-dihydro-1H-isoindol-1-ylidene]arenamines 3a, b , N, N'-[2-aryl-1H-isoindole-1,3(2H)-diylidene]bisarenamines 4a, b and N-arylphthalimides 5a-c in moderate yields. 2,4,7-Trinitro-9-fluorenone as well as one reduction product each of the latter and of A, namely compounds 6 and 7 , respectively, are also found. The structure of 2b has been unambiguously confirmed by an X-ray crystal structure analysis. A rationale for the conversions observed is presented. These involve dehydrogenation and oxidative couplings of 1a-c as well as transfer of N-aryl fragment from 1a-c to intermediate products.     

Heterocyclic compounds from 3,3-dimercapto-1-aryl-2-propen-1-ones. Note 1. 4-Ary1-1,3-dihydro-2H-1,5-benzodiazepine-2-thiones

A series of new 4-aryl-1,3-dihydro-2H-1,5-benzodiazepine-2-thiones ( 3 ) has been synthesized by condensing the 3,3-dimercapto-1-aryl-2-propen-1-ones with o-phenylenediamine. The structure was established by the results of acid cleavage and by nmr spectra. The alkylation of compounds 3 gave 2-alkylthio-4-aryl-3H-1,5 benzodiazepines ( 10 ).     

Synthesis of derivatives of a new heterocyclic system,indolo[2,3-f][1,7]naphthyridine

3-(N"-Aryl-N"-chloroacetyl)amino-2-formylindoles were converted into 3-amino-1-aryl-2-oxo-1,2-dihydropyrido[3,2-b]indoles, which were used to synthesize derivatives of a new heterocyclic system, namely, indolo[2,3-f][1,7]naphthyridine. The structures of the resulting compounds were proved by IR and ¹H NMR spectroscopy and mass spectrometry.     

N-Aryl-2-dialkylaminosuccinimides

Reaction of N-arylmaleimides with an equimolar amount of diethylamine, piperidine, and morpholine afforded the corresponding N-aryl-2-dialkylaminosuccinimides as mixtures of stereoisomers.     

Cyclopropanation of N-Substituted 2-Oxochromene- and 6-Bromo-2-oxochromene-3-carboxamides with Zinc Enolates Derived from 1-Aryl-2,2-dibromoalkanones

Zinc enolates derived from 1-aryl-2,2-dibromoalkanones react with N-cyclohexyl-2-oxochromene-3-carboxamides to give N-cyclohexyl-1-alkyl-1-aroyl-2-oxo-1a,7b-dihydrocyclopropa[c]chromene-1a-carboxamides mainly as cis isomers with respect to the substituents in positions 1 and 1a. Reactions of the same zinc enolates with N-benzyl-2-oxochromene-3-carboxamide and N-benzyl-6-bromo-2-oxochromene-3-carboxamide lead to formation of 1-aryl-2-benzyl- and 1-aryl-2-benzyl-6-bromo-1-hydroxy-9c-alkyl-1,2,9b,9c-tetrahydro-5-oxa-2-azacyclopenta[2,3]cyclopropa[1,2-a]naphthalene-3,4-diones. The reaction of zinc enolates with N-aryl-2-oxochromene-3-carboxamides in a weakly polar solvent (diethyl ether or ethyl acetate) affords mixtures of cis-N-aryl-1-aroyl-1-alkyl-2-oxo-1a,7b-dihydrocyclopropa[c]chromene-1a-carboxamides and their cyclic isomers, 9c-alkyl-1,2-diaryl-1-hydroxy-1,2,9b,9c-tetrahydro-5-oxa-2-azacyclopenta[2,3]cyclopropa[1,2-a]naphthalene-3,4-diones, the latter prevailing. N-Substituted 1-alkyl-1-aroyl-2-oxo-1a,7b-dihydrocyclopropa[c]chromene-1a-carboxamides in which the aroyl group on C¹ and the carboxamide group on C^1a are arranged trans are formed by reactions of zinc enolates with the corresponding 2-oxochromene-3-carboxamides in the presence of hexamethylphosphoric triamide.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 4, 2005, pp. 539–546.Original Russian Text Copyright © 2005 by V. Shchepin, Silaichev, R. Shchepin, Ezhikova, Kodess.     

α-Nitro chalcones: Structure and reaction with pyrrole

According to the ¹H NMR, IR, and electronic absorption spectra and X-ray diffraction data, 2-aryl-1-benzoyl-1-nitroethenes have E configuration with predominant s-cis conformation, where the nitro group lies in the plane of the double carbon-carbon bond, while the carbonyl group deviates from that plane. Reactions of 2-aryl-1-benzoyl-1-nitroethenes with pyrrole and N-methylpyrrole gave the corresponding alkylation products at the C² atom in the heteroring.     

Synthesis of 1-aryl-2-[2-(dimethylamino)ethyl]-1,2-dihydrochromeno[2,3-c]pyrrole-3,9-diones and their analogs

Methyl o-hydroxybenzoylpyruvate heated with N,N-dimethylethylenediamine and aromatic aldehydes affords in a high yield 5-aryl-3-hydroxy-4-(2-hydroxyphenyl)-1-[2-(dimethylamino)ethyl]-1,5-dihydro-2H-pyrrol-2-ones, which easily split off water at boiling in acetic acid and are converted into 1-aryl-2-[(2-dimethylamino)ethyl]-1,2-dihydrochromeno[2,3-c]pyrrol-3,9-diones. The developed route of synthesis provides a wide range of derivatives of 1-aryl-2-[ω-(dialkylamino)alkyl]-1,2-dihydrochromeno[2,3-c]pyrrole-3,9-diones.     

Synthesis of 6-aryl-1,3-dimethyl-6,7-dihydro-6-azalumazin-7-(6H)ones and their conversion into 2-aryl-1,2,4-triazine-3,5-(2H,4H)odiones. A new synthesis of 1-aryl-6-azauracils

Treatment of 6-amino-5-arylazo-1,3-dimethyluracils with urea or N,N′-carbonyldiimidazole gave the respective 6-aryl-1,3-dimethyl-6,7-dihydro-6-azalumazin-7-(6H)ones, which were hydrolyzed with alkali to afford 2-aryl-2,3,4,5-tetrahydro-3,5-dioxo-1,2,4-triazine-6-carboxylic acids (1-aryl-6-azauracil-5-carboxylic acids). Thermal decomposition of these carboxylic acids gave the corresponding 2-aryl-1,2,4-triazine-3,5-(2H,4H)diones (1-aryl-6-azauracils). Methylation of the latter with methyl iodide gave the corresponding 2-aryl-4-methyl-1,2,4-triazine-3,5-(2H,4H)diones (1-aryl-3-methyl-6-azauracils).     

5-Aryl-2-furaldehydes in the Synthesis of 2-Substituted 1,3-Benzazoles

2-[2-(5-Aryl-2-furyl)ethenyl]-1,3-benzazoles were synthesized by reaction of 5-aryl-2-furaldehydes with 2-methylbenzoxazole, 2-methylbenzothiazole, 2-methylbenzimidazole, and 2-cyanomethylbenzimidazole. The corresponding benzazoles were also obtained by reaction of N-(5-arylfurfurylidene)anilines with 2-methylbenzoxazoles and of 3-(5-aryl-2-furyl)-2-cyanopropenoyl chlorides with o-phenylenediamine. The acylation of o-aminophenol with 3-(5-aryl-2-furyl)-2-cyanopropenoyl chlorides occurs at the amino group without subsequent oxazole ring closure.     

Electron impact studies—LXV: Negative-ion mass spectrometry of functional groups 2-aryl-1,3-dithianes

The negative-ion mass spectra of 2-aryl-1,3-dithianes contain pronounced molecular anions together with fragment ions which are produced by both simple and complex cleavage reactions. These spectra contain further examples of specific hydrogen scrambling processes in negative ions. Nitroaryldithianes give intense negative-ion spectra, and that of the o-nitro derivative exhibits an unusual proximity effect. The fragmentation patterns have been examined using both ²H and ¹³C labelling and the metastable defocusing technique.     

Synthesis and Electrospray Ionization Mass Spectra of N-（1,3, 2-Dioxaphosphorinan-2-ylmethyl）thiophosphoramidates

N-（1,3,2-Dioxaphosphorinan-2-ylmethyl）thiophosphoramidates were synthesized and determined by NMR spectra and positive ion electrospray ionization mass spectrometry （ESI-MS） in conjunction with tandem mass spectrometry （MS/MS）. The fragmentation pathways were investigated. The results show that these characteristic ions in ESI mass spectra are useful in the structural determination of N-（1,3,2-dioxaphosphorinan-2-ylmethyl）- thiophosphoramidates.     

Synthesis and Properties of N-(2,2,2-Trichloroethyl)-2-thiophenesulfonamides

Chlorination of 2-thiophenesulfonamide gave unstable N,N-dichloro-2-thiophenesulfonamide which was brought into reactions with 1,2-polyhaloethenes. The condensation of 2-thiophenesulfonamide with trichloroacetaldehyde afforded N-(2,2,2-trichloro-1-hydroxyethyl)-2-thiophenesulfonamide which reacted with benzene, toluene, 2-chlorothiophene, and phenol to form the corresponding N-(1-aryl-2,2,2-trichloroethyl)-2-thiophenesulfonamides. Under more severe conditions, the latter were converted into 1,1-diaryl-2,2,2-trichloroethanes. The reaction of N-(2,2,2-trichloro-1-hydroxyethyl)-2-thiophenesulfonamide with substituted arenes, including phenol, was regioselective: only the corresponding para-substituted products were obtained. Hydrolysis of N-[2,2,2-trichloro-1-(4-tolyl)ethyl]-2-thiophenesulfonamide yielded N-(2-thienylsulfonyl)-2-(4-tolyl)glycine.