Kinetic evidence for remote pi-aryl participation in the BF3-catalyzed rearrangement of [2 + 2] photocycloadducts of diarylhomobenzoquinones with diphenylacetylene.
[reaction: see text] The BF(3)-catalyzed rearrangement of cyclobutene-fused m- and p-substituted diarylhomobenzoquinones exclusively gave the keto-alcohols via a Wagner-Meerwein vinyl-anion migration followed by the annulation of a delta-located endo-aryl group. The Hammett treatments for the endo/exo substituent effects, as well as the kinetic solvent effects, indicated that this reaction proceeds through the concerted S(N)2-like mechanism involving a rate-determining endo-aryl-assisted transition state.
Koizumi
Takuya
T
Department of Materials Chemistry, Graduate School of Engineering, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Harada
Kenji
K
Mochizuki
Eiko
E
Kokubo
Ken
K
Oshima
Takumi
T