C. Conesa et Hs. Rzepa, Re-engineering potential energy surfaces: trapezoidally distorted (pi)2(s)+(pi)2(s) thermal cycloaddition/elimination reactions, J CHEM S P2, (12), 1998, pp. 2695-2698
Citations number
14
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2
Calculations at the PM3 or B3LYP/6-31G(d) SCF-MO levels of theory indicate
that electron-withdrawing substituents can modify the potential energy surf
ace for a simple thermal (pi)2(s) + (pi)2(s) pericyclic cycloaddition-elimi
nation via a trapezoidal geometric distortion. We propose this thermally al
lowed synchronous reaction mode as an alternative to the Woodward-Hoffmann
antarafacial mode or the stepwise biradical pathways normally invoked for s
uch thermally activated cycloadditions. Reaction of the substituted syn tri
cyclic system 1 via the trapezoidal and synchronous transition state 6 is p
redicted as a potential experimental test of this new reaction mode.