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Facial selectivities and rate effects in the thermal [4+2] dimerization of arylated 1,3‐dienes. 1,5‐H shift versus dimerization of ( Z )‐1,3‐Dienes
Author(s) -
Mulzer Johann,
Kühl Uwe,
Huttner Gottfried,
Evertz Kaspar
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.19881211223
Subject(s) - chemistry , aryl , alkyl , diene , diradical , medicinal chemistry , reactivity (psychology) , selectivity , stereochemistry , organic chemistry , medicine , natural rubber , physics , alternative medicine , pathology , nuclear physics , singlet state , excited state , catalysis
For the thermal [4+2] dimerization of the dienes 1 and 4 a parallel increase in facial selectivity and reaction rate is observed on going from the ( E )‐alkyl‐aryl dienes 1h – m and the ( Z )‐dienes 4a, b to the ( E )‐aryl‐aryl dienes 1a – f . This phenomenon is interpreted in terms of the resonance stabilization of a diradical intermediate 8 . The ( Z )‐dienes 4c, d show a sigmatropic 1,5‐H shift instead of a dimerization on heating.