Unexpected stereodynamic consequences of the restricted rotations in ortho-acyl- and ortho-vinyl biphenyls.
Surprisingly, the aryl-aryl rotation barriers of biphenyl derivatives ortho-substituted by the "small" HC=O and HC=CH2 groups (10.0 and 8.4 kcal mol-1, respectively) were found greater than those observed in biphenyls ortho-substituted by the "large" t-BuC=O and t-BuC=CH2 groups (6.7 and 6.9 kcal mol-1, respectively).
Lunazzi
Lodovico
L
Department of Organic Chemistry A. Mangini, University of Bologna, Viale Risorgimento, 4 Bologna 40136, Italy.
Mazzanti
Andrea
A
Minzoni
Mirko
M