Factors affecting ease of ring formation. The effect of anchoring substitution on the rate of an intramolecular diels-alder reaction with furan-diene

Abstract

Kinetic parameters for the IMDAF reaction of 2 and 3 were determined. For the equilibrium between 2b and 4b: ΔH° = -29.3 kJ/mol, ΔS° = -75 J/mol.K; for the conversion of 3 into 6 a significant rate enhancement by the anchoring tert-butyl group is observed: k(3b)/k(3a) = 240. The structure of 6b was proven via X-ray determination of 8. © 1988