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On the mechanism of photoinduced addition of acetonitrile to phosphonium–iodonium ylides
Author(s) -
Nekipelova Tatiana D.,
Kuzmin Vladimir A.,
Matveeva Elena D.,
Gleiter Rolf,
Zefirov Nikolay S.
Publication year - 2013
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.2972
Subject(s) - chemistry , photochemistry , heterolysis , homolysis , phosphonium , acetonitrile , bond cleavage , phosphonium salt , photodissociation , tetraphenylethylene , singlet state , medicinal chemistry , salt (chemistry) , organic chemistry , excited state , radical , catalysis , fluorescence , physics , quantum mechanics , nuclear physics , aggregation induced emission
Recently, a novel photochemical reaction of pseudocycloaddition of nitriles to mixed phosphonium–iodonium ylides 1 was found. Nitriles R 1 CN give corresponding oxazoles (2) with a high yield, with PhI (3) being a leaving group. The mechanism of the photoinduced cycloaddition of acetonitrile to mixed phosphonium–iodonium ylide 1 was studied by steady‐state and time‐resolved methods with resolution from 10 ns to 20 µs. The formation of photolysis products, substituted oxazole 2, and phosphonium salt 4, occurs in parallel reactions. The primary photochemical processes for the formation of 2 and 4 are the heterolytic and homolytic C–I + Ph bond cleavage in the excited singlet state of 1, respectively. Three transient species with lifetimes on microsecond and millisecond time scales were observed. The mechanism of the formation of major and minor products of the photolysis was suggested. Addition of water to the reaction mixture in acetonitrile changes the ratio of the products in favor of the phosphonium salt formation. The effect of water was accounted for by the acid catalysis of the homolytic C–I + Ph bond cleavage and the acceleration of the salt formation. Copyright © 2012 John Wiley & Sons, Ltd.