83867-89-4Relevant academic research and scientific papers
ACYLOTROPIC TAUTOMERISM. XV. EFFECT OF SUBSTITUENTS IN THE SEVEN-MEMBERED RING ON THE KINETICS OF TAUTOMERIC TRANSFORMATIONS AND THE STEREODYNAMICS IN O-ACYL DERIVATIVES OF TROPOLONES
Olekhnovich, L. P.,Borisenko, N. I.,Budarina, Z. N.,Metlushenko, V. P.,Zhdanov, Yu. A.,Minkin, V. I.
, p. 1561 - 1570 (2007/10/02)
The kinetics of acylotropy and their dependence on the electronic and steric effects of substituents at positions 3, 5, 7 of the seven-membered ring were studied by dynamic 1H and 13C nuclear magnetic resonance for a wide range of O-acyl derivatives of tropolones.Withdrawing substituents retard acylotropy, but at positions 3 bulky substituents help sterically to accelerate the O,O'-acyl migrations.In the PMR spectra the prochiral methylene groups of 2-acyloxy-3,7-dibenzyltropones record the stereodynamic processes of restricted rotation in the acyloxy fragments.The rates of O,O'-transfer and the accompanying rotational movements are equalized with increase in the migratory aptitude of the acyl.For fast migrants there is an effective correlation betwen the acylotropy and the stereodynamics with identical activation parameters 5-9 kcal/mole>.
