Negative-ion mass spectra of diterpene alkaloids with the keto group in the 6- or 7-position

Processes resulting in the formation of negative ions by molecules of some diterpene alkaloids via resonance electron capture have been studied. The mass spectra of these compounds have a small number of lines represented largely by intense peaks in the thermal electron energy region and are due to electron capture onto the lower unoccupied molecular orbital, which is π*-C=O or π*-Ph-C=O in character.     

Negative-ion mass spectra of the synthetic alkaloid diptocarpilidine and its deoxy precursor

The existence of the molecules of the synthetic alkaloid diptocarpilidine in a folded conformation as a consequence of the intramolecular interaction of the sulfoxide and cyano groups through space has been established by negative-ion mass spectrometry. Institute of Organic Chemistry, Urals Branch, Russian Academy of Sciences, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 543–546, September–October, 1992.     

Oxidation of diazo compounds by triphenyl phosphite ozonide. Quenching of singlet oxygen by diazo compounds

The reaction of triphenyl phosphite ozonide with various types of diazo compounds results in their oxidation, which is accomplished by singlet oxygen (¹O₂) evolved during thermal decomposition of the ozonide. A decrease in the ionization potential of the substrate results in an increase in the overall rate constant of quenching of¹O₂. In the case of 9-diazofluorene, the main channel of¹O₂ quenching is physical quenching.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1567–1571, September, 1994.The work was carried out with the financial support of the Russian Foundation for Basic Research (Project No. 93-03-5231).     

Dissociative electron capture by 1,3-dithiolanes and 1,3-dioxalanes

A study was carried out on dissociative electron capture by 1,3-dithiolanes and 1,3-dioxalanes. The mechanisms for the fragmentation pathways of the negative ions differ significantly between the oxygen- and sulfur-containing compounds. The (M-H)^– ions are formed with excess internal excitation energy.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 208–210, January, 1990.     

Mass spectra of the negative ions of some dioxanes

It was established by mass spectrometry of negative ions that fragmentation of some 1,3- and 1,4-dioxanes proceeds through intermediate [M-H]⁻ ions. The fragmentation pathway depends on the site of negative charge localization in these ions. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2199–2201, November, 1999.     

Sulfur ylides

The mass spectra of negative ions of keto-stabilized sulfur and phosphorus ylides (obtained from amino acids) and products of their thermal conversion are studied. The most characteristic peaks in the mass spectra of ylides belong to negative molecular ions and to [M−H]⁻ ions. Peaks of fragment ions in the mass spectra of ylides and products of their thermal conversion coincide both in mass numbers and resonance energies. For Part 8, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2100–2103, November, 1999.     

Dissociative electron capture by sulfide,sulfoxide, and sulfone molecules

Conclusions The low energy resonance in the negative ion mass spectra of alkyl vinyl, 2,3-epoxypropyl alkyl, and 2, 3-epithiopropyl alkyl sulfies and their sulfoxide and sulfone analogs is related to electron capture in the ^* orbital of the S-C bond. The oxidation state of the sulfur atom has no qualitative effect on the major processes involved in the formation of the negative ions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, 1653–1657, July, 1984.     

Linear cooligomerization of vinylsilanes with butadiene as a method for the synthesis of silicon-containing polyenes

Conclusions We have developed a method for the synthesis of silicon-containing polyenes from butadiene and trimethylvinylsilane or trimethoxyvinylsilane with a Ni-containing catalyst system. We suggest a reaction sequence for the cooligomerization process.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 599–604, March, 1979.