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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Mechanism of Photochemical O-Atom Exchange in Nitrosamines with Molecular Oxygen

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Oliveira, Marlene Silva [1, 2, 3] ; Ghogare, Ash-Wini A. [2, 3] ; Abramova, Inna [2, 3] ; Greer, Edyta M. [4] ; Prado, Fernanda Manso [1] ; Di Mascio, Paolo [1] ; Greer, Alexander [2, 3]
Total Authors: 7
[1] Univ Sao Paulo, Inst Quim, Dept Bioquim, BR-05508000 Sao Paulo - Brazil
[2] CUNY Brooklyn Coll, Dept Chem, Brooklyn, NY 11210 - USA
[3] CUNY Brooklyn Coll, Grad Ctr, Brooklyn, NY 11210 - USA
[4] CUNY, Dept Nat Sci, Baruch Coll, New York, NY 10010 - USA
Total Affiliations: 4
Document type: Journal article
Source: Journal of Organic Chemistry; v. 80, n. 12, p. 6119-6127, JUN 19 2015.
Web of Science Citations: 2

The detection of an oxygen-atom photoexchange process of N-nitrosamines is reported. The photolysis of four nitrosamines (N-nitrosodiphenylamine 1, N-nitroso-N-methylaniline 2, N-butyl-N-(4-hydroxybutypnitrosamine 3, and N-nitrosodiethylamine 4) with ultraviolet light was examined in an O-18(2)-enriched atmosphere in solution. HPLC/MS and HPLC-MS/MS data show that O-18-labeled nitrosamines were generated for 1 and 2. In contrast, nitrosamines 3 and 4 do not exchange the 180 label and instead decomposed to amines and/or imines under the conditions. For 1 and 2, the O-18 atom was found not to be introduced by moisture or by singlet oxygen {[}(18)(O-1(2) (1)Delta(g)] produced thermally by O-18-O-18 labeled endoperoxide of N,N'-di(2,3-hydroxypropyl)-1,4-naphthalene dipropanamide ((DHPNO2)-O-18) or by visible-light sensitization. A density functional theory study of the structures and energetics of peroxy intermediates arising from reaction of nitrosamines with O-2 is also presented. A reversible head-to-tail dimerization of the O-nitrooxide to the 1,2,3,5,6,7-hexaoxadiazocane (30 kcal/mol barrier) with extrusion of O=O-18 accounts for exchange of the oxygen atom label. The unimolecular cyclization of O-nitrowdde to 1,2,3,4-trioxazetidine (46 kcal/mol barrier) followed by a retro {[}2 + 2] reaction is an alternative, but higher energy process. Both pathways would require the photoexcitation of the nitrooxide. (AU)

FAPESP's process: 12/12663-1 - Singlet molecular oxygen and peroxides in chemical biology
Grantee:Paolo Di Mascio
Support type: Research Projects - Thematic Grants
FAPESP's process: 13/07937-8 - Redoxome - Redox Processes in Biomedicine
Grantee:Ohara Augusto
Support type: Research Grants - Research, Innovation and Dissemination Centers - RIDC