Premium
Local HSAB principle in the conjugate addition of p ‐substituted thiophenols to cyclohexenone
Author(s) -
Meza Rocío,
Gordillo Bárbara,
Galván Marcelo
Publication year - 2005
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.20577
Subject(s) - hsab theory , chemistry , ring (chemistry) , conjugate , density functional theory , computational chemistry , substituent , delocalized electron , conjugated system , electrophile , photochemistry , medicinal chemistry , organic chemistry , mathematical analysis , mathematics , catalysis , polymer
In the formation of new bonds through the Michel‐type addition of thiolates to a α,β‐conjugate system, it is observed that the reaction takes place faster if the thio donor compound contains an electron‐rich group or the enone acceptor is highly electron deficient. In contrast, the hard–soft acid–base (HSAB) principle predicts that this reaction is favored when a soft–soft interaction between the reactants takes place. Taking into account that softness is related to a barely electronegative atom of high polarizability, we consider it of interest to analyze the effect of charge transfer of a p ‐substituent on the softness of sulfur in thiophenols, as well as its impact in the conjugate addition to 2‐cyclohexen‐1‐one. Experiments‐in‐competition, net charge of X‐groups at the p ‐position of the aromatic ring, the global and local softness at sulfur, and the electrophilicity, obtained by density functional theory (DFT), led to the observation that the reaction is faster for electron attractor thiophenols. The softness at sulfur increases by delocalization of charge through the aromatic ring. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005