TY - JOUR

T1 - Mechanistic Aspects of Photoinduced Rearrangement of 2,3-Diarylcyclopentenone Bearing Benzene and Oxazole Moieties

AU - Glebov, Evgeni M.

AU - Ruban, Natalia V.

AU - Pozdnyakov, Ivan P.

AU - Grivin, Vjacheslav P.

AU - Plyusnin, Victor F.

AU - Lvov, Andrey G.

AU - Zakharov, Alexey V.

AU - Shirinian, Valerii Z.

N1 - Publisher Copyright: © 2018 American Chemical Society.

PY - 2018/8/21

Y1 - 2018/8/21

N2 - Photoinduced rearrangement of diarylethenes to naphthalenes or isoelectronic benzoannulated heterocycles is a novel reaction in preparative organic photochemistry. Recently it was shown that unsymmetrical diarylethenes containing benzene and oxazole derivatives efficiently undergo this transformation leading to amide derivatives of naphthalene. Mechanistic study of skeletal rearrangement for a typical representative of these compounds, namely 3-(5-methyl-2-phenyl-1,3-oxazol-4-yl)-2-phenylcyclopent-2-en-1-one, was performed by stationary and laser flash photolysis as well as density functional theory (DFT) calculations. The mechanism of the rearrangement was found to comprise several thermal stages. Both singlet and triplet states of the initial compound can be transformed to the reaction product, which results in the dependence of the quantum yield vs concentration of dissolved oxygen. Three reactive intermediates were registered in the laser flash photolysis experiment; the predicted structures were in accordance with DFT calculations of the electronic absorption spectra. In addition to the previously proposed mechanism of skeletal rearrangement based on a sigmatropic shift of hydrogen, two new parallel pathways based on formation of a carbanion/carbocation were determined.

AB - Photoinduced rearrangement of diarylethenes to naphthalenes or isoelectronic benzoannulated heterocycles is a novel reaction in preparative organic photochemistry. Recently it was shown that unsymmetrical diarylethenes containing benzene and oxazole derivatives efficiently undergo this transformation leading to amide derivatives of naphthalene. Mechanistic study of skeletal rearrangement for a typical representative of these compounds, namely 3-(5-methyl-2-phenyl-1,3-oxazol-4-yl)-2-phenylcyclopent-2-en-1-one, was performed by stationary and laser flash photolysis as well as density functional theory (DFT) calculations. The mechanism of the rearrangement was found to comprise several thermal stages. Both singlet and triplet states of the initial compound can be transformed to the reaction product, which results in the dependence of the quantum yield vs concentration of dissolved oxygen. Three reactive intermediates were registered in the laser flash photolysis experiment; the predicted structures were in accordance with DFT calculations of the electronic absorption spectra. In addition to the previously proposed mechanism of skeletal rearrangement based on a sigmatropic shift of hydrogen, two new parallel pathways based on formation of a carbanion/carbocation were determined.

KW - MOLECULAR-OXYGEN

KW - SINGLET OXYGEN

KW - TRIPLET-STATES

KW - PHOTOCHEMICAL-REARRANGEMENT

KW - EXCITED SINGLET

KW - DIARYLETHENES

KW - PHOTOCYCLIZATION

KW - CONSTRUCTION

KW - STABILITY

KW - CHEMISTRY

UR - http://www.scopus.com/inward/record.url?scp=85063338616&partnerID=8YFLogxK

U2 - 10.1021/acs.jpca.8b05212

DO - 10.1021/acs.jpca.8b05212

M3 - Article

C2 - 30126277

AN - SCOPUS:85063338616

VL - 122

SP - 7107

EP - 7117

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

SN - 1089-5639

IS - 36

ER -