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Electron‐transfer photochemistry of benzocyclobutenes stereospecific electrocyclic reactions of their cation radicals
Author(s) -
Takahashi Yasutaka,
Kochi Jay K.
Publication year - 1988
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19881210210
Subject(s) - chemistry , tetracyanoethylene , photochemistry , chloranil , conrotatory and disrotatory , electron transfer , radical , valence (chemistry) , reactive intermediate , radical ion , electrocyclic reaction , acceptor , ion , stereochemistry , bicyclic molecule , organic chemistry , physics , condensed matter physics , catalysis , ring (chemistry)
The facile activation of cis ‐ and trans ‐1,2‐diphenylbenzocyclobutene (DBC) either by charge‐transfer irradiation of the electron donor‐acceptor complex with tetracyanoethylene or by chloranil photosensitization leads to a series of rapid [4 + 2] cycloadditions. The role of the cation radical DBC +. as the reactive intermediate which undergoes a stereospecific, conrotatory cycloreversion is delineated, especially with regard to “contact” and “solvent‐separated” ion pairs. Such cycloadditions induced by electron transfer are discussed in the context of the thermal valence tautomerization of DBC previously established by Huisgen, Quinkert, and co‐workers.