Thermal [ π2 s+ π2 s+ π2 s]-cycloaddition of thiobenzophenone to substituted phenylallenes. Hammett correlation of rates and ionization energies

Abstract

Thiobenzophenone reacts as an electrophile in the thermal [ π2 s+ π2 s+ π2 s]-cycloaddition reaction with substituted phenylallenes, was deduced from a linear free energy correlation of the reaction rates σ + (ϱ + = −0.36 ± 0.03 (n=9, r=0.97)) and with the first ionization energies IE a (log(k X/k H) = −0.55 IE a + 4.57 (r=0.92)) of the substituted phenylallenes. Additional evidence for the mechanism is given.