Premium
Pseudopericyclic design drives antara‐antara [1,5] methylene sigmatropic shifts from a stepwise to a concerted mechanism
Author(s) -
López Carlos Silva,
Faza Olalla Nieto,
Souto José A.,
Álvarez Rosana,
De Lera Ángel R.
Publication year - 2007
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20620
Subject(s) - sigmatropic reaction , chemistry , heteroatom , concerted reaction , allene , computational chemistry , cyclopropane , stereochemistry , methylene , transition state , photochemistry , medicinal chemistry , ring (chemistry) , organic chemistry , catalysis
Antara‐antara [1,5]‐methylene sigmatropic shifts of propenylidene cyclopropane and its heteroanalogues are shown to proceed through concerted or stepwise mechanisms depending on a delicate balance that is directly related to the presence or absence of heteroatoms at the termini atoms of the rearrangement. Lowering of activation energies upon heteroatom replacement are more significant for the oxacyclopropane analogues 1D, 1E , and 1F but double heterosubstitution is still needed to achieve a pseudopericyclic reaction. In fact only after reaching a pseudopericyclic process the energy balance favors the concerted pathway. Negligible NICS values and a clear disconnection in the ACID plot as well as some structural and energetical parameters reveal the pseudopericyclic nature of this concerted antara‐antara [1,5] CH 2sigmatropic shift. Although the product of the pseudopericyclic process is unprecedented, similar cycloisomerizations after allene activation should be considered within this hitherto undescribed reactions. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007