The Walden cycle revisited: a computational study of competitive ring closure to alpha- and beta-lactones.
The text-book Walden cycle which interconverts the stereochemical configurations of chlorosuccinic and malic acids involves a beta-lactone intermediate in preference to an alpha-lactone intermediate because the O(nuc) C Cl angle in the transition structure for the former (174 degrees) is more favourable than that for the latter (139 degrees), as determined by PCM(epsilon = 78.4)/B3LYP/6-31+G* calculations; the smaller ring-strain energy of the beta-lactone contributes little to the reactivity difference.
Buchanan
J Grant
JG
Department of Chemistry, University of Bath, UK.
Diggle
Richard A
RA
Ruggiero
Giuseppe D
GD
Williams
Ian H
IH