Site selectivity switch in Lewis acid catalysis. Mechanism and kinetic simulation of skeletal rearrangement of cyclobutene-fused homoquinones.
[reactions: see text] We investigated the site selectivity switch in BF3-catalyzed dual skeletal rearrangements of cyclobutene-fused diarylhomobenzoquinones by changing the stoichiometric amount of acid concentration. From the lower to the higher equivalency of BF3 x Et2O, the branching product ratios (path A/path B) obeyed nonlinear sigmoid curves against the equivalency of BF3 x Et2O. The observed selectivity profiles were simulated to elucidate factors that govern thermodynamic aspects (binding affinity K of each carbonyl function with acid) and kinetic aspects (rate constants k for the cyclobutene-ring cleavage).
Kokubo
Ken
K
Division of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
Koizumi
Takuya
T
Harada
Kenji
K
Mochizuki
Eiko
E
Oshima
Takumi
T