Nuclear magnetic resonance spectra of substituted tetraphenylmethylenediphosphine dioxides

Conclusions We studied nuclear magnetic resonance spectra of substituted dioxides of tetraphenylmethylenediphosphine in a medium of trifluoroacetic acid or chloroform. The chemical shifts measured in chloroform satisfactorily agree with Hammett's . Trifluoroacetic acid levels the effect of substituents.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 419–421, February, 1968.     

Nuclear magnetic resonance spectra of pyrido- and azapyridocyanines

The nuclear magnetic resonace spectra of six pyridocyanines, four azapyridocyanines, one monoquaternized 2,4′-dipyridylamine and two dipyridylamines were measured and fully analyzed. The spectra of the 2,2′-pyrido- and azapyridocyanines support previously published results that these dyes exist in the all-trans form and not in the mono-cis form, as stated by others. Strong evidence was obtained that N,N′-ethylene-2,2′-pyridocyanine is twisted. The spectra of dyes with p-connected pyridine rings indicate that these nuclei may rotate around the bond between the meso group and the p-position. Relative chemical shifts in the spectra of the homologous pyrido- and azapyridocyanines can be explained by electronic effects rather than by magnetic anisotropy of the aza group or changes in ring currents.     

Nuclear magnetic resonance spectra of codeine and isocodeine derivatives

The NMR spectra of a spiro oxirane ( 1 ) derivative of codeinone, codeine ( 2 ), isocodeine ( 3 ), 6-methylcodeine ( 4 ) and 6-methylisocodeine ( 5 ) were compared. NOE and double-resonance experiments were used to confirm the conformation of 1 , and the configuration about C-6 of 6-methylcodeine and 6-methylisocodeine. An interchange of the chemical shifts of the olefinic protons in 1 was noted, as compared with those in all of the other compounds. This interchange could be attributed to the bond anisotropies of the oxirane moiety.     

Nuclear magnetic resonance spectra under chemical polarization conditions

Russian Chemical Bulletin -     

The mass spectra of some alkyl and aryl oxazoles

The mass spectra of a variety of alkyl and aryl oxazoles have been determined and the spectra analyzed with the aid of deuterium labelling and high resolution mass spectrometry. In contrast to the corresponding benzenoid compounds, the mass spectra of isomeric alkyl oxazoles are distinctive and in this respect are akin to those of the corresponding pyridines. Further analogy to the pyridines is suggested by the unfavorable nature of a carbonium ion adjacent to the 2-position and this effect may be used to locate alkyl substituents attached to the oxazole nucleus. The loss of carbon monoxide from the molecular ions of 2,5-disubstituted oxazoles probably occurs with ring opening and migration of the C-5 substituent (e.g.Br) to the C-4 position.     

Nuclear magnetic resonance spectra of tropic acid and some derivatives

The NMR spectra of tropic acid, its methyl ester and acetyltropic acid methyl ester were measured at 100 and 220 MHz in various solvents. The spectra were analysed by means of an iterative computer procedure. The results indicate, for all the compounds studied, a predominance of the conformation where the phenyl and hydroxyl (or acetoxyl) groups are in anti.positions to each other. The solvent and concentration effects upon the vicinal coupling constants and hence upon the position of the conformational equilibria are rather weak.     

Synthesis of substituted oxazolidinones from compounds of the ethylene series

The reaction of N-bromocarbamates with ethylene compounds was investigated, and the high structural specificity of this reaction was demonstrated. The structures of the (-bromocarbamates obtained were confirmed by their IR and PMR spectra. When they are heated to 602-13D°C, they are readily cyclized to the corresponding oxazolidinones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1628–1630, December, 1979.Original article submitted December 11, 1978.     

Nuclear magnetic resonance spectra of mixtures of 2-monohydroperfluoroisobutane and triethylamine

Conclusions The presence of a strong hydrogen bond between 2-monohydroperfluoroisobutane and triethylamine has been established by the NMR method. Thehydrogen bond shift in this system is not less than 2 p.p.m.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1342–1343, June, 1967.     

13C Nuclear magnetic resonance studies of some substituted thiols and thioanisoles

¹³C NMR spectra of thiophenol, 4-nitrothiophenol, 4-X-thioanisole (X = NO₂, NH₂, SH, H) were examined in CDCl₃ solution. Substituent chemical shift values (additivity parameters) for the −SH and −SCH₃ groups are reported.In para-substituted thioanisoles, while the −NH₂ group caused a deshielding and −NO₂ a shielding of SCH₃ carbon resonance, −SH appeared to have had no effect on the carbon resonance.     

A method for the parallel synthesis of multiply substituted oxazolidinones

There are many examples of both naturally occurring and synthetic molecules containing a 2-oxazolidinone ring that have significant biological activity. The oxazolidinone ring potentially has three sites for attachment of diversity elements. A synthesis that can provide for inclusion of diversity elements at all three positions should be a powerful method for the preparation of oxazolidinone libraries. In this paper we present the preparation of a 3 x 3 x 3 array yielding 27 different products with minimal workup, high yields, and, most importantly, high purity. Using an intramolecular acylnitrene-mediated aziridination reaction, we have prepared (triphenylmethoxymethyl)-3-oxa-1-azabicyclo[3.1.0]hexan-2-one as a starting material for library generation. The first substitution involves opening the aziridine ring of the azabicyclo[3.1.0]hexane ring system using a Grignard reagent. The nitrogen of the oxazolidinone is now ready for substitution via alkylation or arylation. Removing the trityl protecting group via esterification under mildly acidic conditions accomplishes the final substitution.     

Nuclear magnetic resonance spectra and structure of some alkyl vinyl sulphides

The NMR spectra of eight alkyl vinyl sulphides have been analyzed and the parameters compared with those obtained from an analogous series of oxygen derivatives. It is shown that a definite parallelism exists between chemical shifts and H? H coupling. Difference in absolute values have been explained by mesomeric interaction involving the ability of sulphur to accommodate a decet of electrons in its valence shell. By analogy with alkyl vinyl ethers, it is possible to predict a similar correlation between the spectral characteristics and relative reactivity of vinyl sulphides in cationic polymerization.     

氨基噻唑类化合物的^1^5N核磁共振研究

氨基噻唑类化合物的结构研究巳有若干报道.但因该类化合物碳原子少,活泼氢原子较多,故~1H和~(13)C核磁共振谱所提供的结构信息少,又因质子位移造成互变异构使结构确定复杂化.本文利用氮-15核磁共振谱对下列六个氨基噻唑类化合物进行较系统的结构分析和互变异构平衡问题的探讨.     

Construction of previously inaccessible 2-amino-4-benzyl substituted oxazoles

A process for the synthesis of 2-amino-4-benzyl-oxazoles is reported.