z-logo
Premium
Evasive Neutral 2‐Aza‐Cope Rearrangements. Kinetic and Computational Studies with Cyclic Nitrones
Author(s) -
Delso Ignacio,
Melicchio Alessandro,
Isasi Arantzazu,
Tejero Tomás,
Merino Pedro
Publication year - 2013
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201300836
Subject(s) - chemistry , cationic polymerization , kinetic energy , toluene , activation energy , catalysis , transition state , solvent , dimethyl sulfoxide , computational chemistry , photochemistry , organic chemistry , physics , quantum mechanics
A full experimental study of the activation energy required for the hitherto unknown neutral 2‐aza‐Cope rearrangement is presented. A kinetic study of the process showed activation energies in the range of 22.91–24.06 kcal/mol, in agreement with a process operating at moderate temperature (70 °C). Calculations at B3LYP/6‐311+G(d,p) and M06‐2X/6‐311+G(d,p) levels of theory considering solvent (dimethyl sulfoxide (DMSO) and toluene) effects (PCM model) predict reaction energy barriers that are in agreement with the values obtained from 1 H NMR‐based kinetic experiments. Results obtained by using enantiomerically pure substrates demonstrate that the rearrangement takes place with complete transfer of chirality, in contrast to previously described cationic processes. The effects of solvent and acid catalysis, which converts the process into the more common cationic rearrangement, have also been studied. DFT calculations also predict correctly the acceleration of the process under acid catalysis, estimating energy barriers in the range of 16.80–18.57 kcal/mol.

This content is not available in your region!

Continue researching here.

Having issues? You can contact us here