Tatiana Yu. Samguina

Lomonosov Moscow State University

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Аlbert T. Lebedev

Northern (Arctic) Federal University

Vita M. Maselli

University of Adelaide

N. K. Karakhanova

Lomonosov Moscow State University

Craig S. Brinkworth

University of Adelaide

Vladislav V. Lobodin

BASF (United States)

A. M. Sipyagin

Russian Academy of Sciences

Daniel Bilusich

Defence Science and Technology Group

John H. Bowie

University of Adelaide

Cooperative Institutions

University of Adelaide

Lomonosov Moscow State University

Moscow State University

Defence Science and Technology Group

University of Wollongong

Division of Chemistry

Institute of Organic Chemistry

Northern (Arctic) Federal University

Animal Hospital Postojna

University of Ljubljana

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Cyclization of N,N-Dialkyldithiocarbamate and Alkylxanthate Derivatives of Polyhalogenated Pyridines in Gas and Liquid Phases

European Journal of Mass Spectrometry (2004)

Tatiana Yu. Samguina Vladislav V. Lobodin N. K. Karakhanova Аlbert T. Lebedev A. M. Sipyagin

The intramolecular cyclization of 31 polyhalogen-substituted pyridines containing N,N-dialkyldithiocarbamate or alkylxanthate groups has been compared as a reaction in solution with sodium N,N-dialkyldithiocarbamates or potassium carbethoxydithiolate and as a gas-phase reaction under electron ionization (EI) conditions. A scheme of fragmentation for the studied compounds has been proposed. The influence of the nature of leaving groups (Cl, F, CF 3 , CN, COOEt), of the presence of electron-withdrawing groups (Cl, F, CN, CCl 3 , CF 3 , COOEt) that are ortho, meta or para to the leaving halogen, of the position of a dithio group with respect to the pyridine nitrogen atom and of the role of oxygen and nitrogen in the corresponding alkylxanthates and N,N-dialkyldithiocarbamates on the cyclization process has been investigated.

Nitrogen atom

Leaving group

10.1255/ejms.595

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Citations (2)

Direct identification of intramolecular disulfide links in peptides using negative ion electrospray mass spectra of underivatised peptides. A joint experimental and theoretical study

Rapid Communications in Mass Spectrometry (2005)

Daniel Bilusich Vita M. Maselli Craig S. Brinkworth Tatiana Yu. Samguina Аlbert T. Lebedev

Abstract [MH] − parent anions of underivatised peptides containing an intramolecular disulfide bridge undergo characteristic loss of the elements of H 2 S 2 , a process diagnostic of the presence of the disulfide moeity. This facile process is initiated from a side‐chain enolate anion. Theoretical calculations (at the HF/6‐31G(d)//AM1 level of theory) indicate that the process is exothermic with a small barrier. When the disulfide link involves a C‐terminal Cys, the negative ion spectrum shows an [(MH)(H 2 S 2 +CO 2 )] fragment anion which is usually the main peak of the spectrum. This process is also directed by an enolate anion: theoretical calculations suggest a stepwise sequence with loss of CO 2 preceding loss of H 2 S 2 . Both [(MH)H 2 S 2 ] and [(MH)(H 2 S 2 +CO 2 )] anions undergo backbone cleavage allowing identification of the amino acid sequence of the peptide. Copyright © 2005 John Wiley & Sons, Ltd.

Cleavage (geology)

10.1002/rcm.2149

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Citations (52)