Photochemistry of N-(selenoalkyl)-Phthalimides. Formation of N, Se-heterocyclic

OKSDATH MANSILLA, GABRIELA; PEÑÉÑORY, ALICIA B.; HEREDIA, ADRIÁN A.; ARGÜELLO, JUAN E.; PEÑEÑEORY, ALICIA A

Photochemical and Photobiological Sciences

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2015 vol. 14 p. 726 - 736

1474-905X

A variety of N-(selenomethyl)alkyl-phthalimides (alkyl = -(CH2)n- ; n = 2-5, 1a, b, d, e) and N- (selenobenzyl)propyl phthalimide (1c) were synthesized and their photochemistry studied at λ = 300 nm. Steady-state photolysis and laser time-resolved spectroscopic studies confirmed that these reactions proceeded by direct or acetone-sensitized excitation followed by intramolecular electron transfer (ET) between the phthalimide moiety and Se atom. Two main pathways are possible after ET: proton transfer to the ketyl radical anion from the CH3Se+? or the -CH2Se+?- moieties, yielding the corresponding biradicals. Collapse of these biradicals yields cyclization products with the respectively endo or exo selenium-containing heterocycles. Competition between both proton transfers depends on the chain length of the alkyl spacer between the phthalimide and Se groups as well as the size of the cycle being formed.