Open AccessBase-catalyzed enolization of 2,5-norbornanediones. Evidence for homoenolic assistance
Author(s) -
Nick Henry Werstiuk,
Roland J. Taillefer,
Sujit Banerjee
Publication year - 1978
Publication title -
canadian journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.323
H-Index - 68
eISSN - 1480-3291
pISSN - 0008-4042
DOI - 10.1139/v78-193
Subject(s) - chemistry , keto–enol tautomerism , catalysis , base (topology) , hydrogen isotope , medicinal chemistry , hydrogen , kinetic isotope effect , organic chemistry , deuterium , mathematical analysis , mathematics , physics , quantum mechanics
The rate enhancements relative to the monoketones, for base-catalyzed exo and endo hydrogen isotope exchange in 2,5-norbornanedione (2), 3,3-dimethyl-2,5-norbornanedione (3), and 1,3,3-trimethyl-2,5-norbornanedione (4) have been determined at 25 ± 0.05 °C in 60% dioxane–40% D 2 O. After the increase in rate due to the inductive and strain effects of the second carbonyl group is taken into account, the homoenolic-assistance factors are extracted from the overall rate enhancements: for exo exchange in 2,3, and 4, the factors are 13, 39, and 32; for endo exchange in 2,3, and 4, the factors are 26, 64, and 71, respectively.