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Deprotonation of Enoxy Radicals: Theoretical Validation of a 50‐Year‐Old Mechanistic Proposal
Author(s) -
Smith David M.,
Buckel Wolfgang,
Zipse Hendrik
Publication year - 2003
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.200250502
Subject(s) - deprotonation , radical , thioester , chemistry , solvation , computational chemistry , ab initio , atom (system on chip) , aqueous solution , solvation shell , organic chemistry , enzyme , molecule , computer science , ion , embedded system
The enhanced acidity at the β position of enoxy radicals may allow enzymes to abstract an aliphatic proton from an unactivated thioester. Although this phenomenon was proposed half a century ago, validation has now been found by combining high‐level ab initio calculations with both implicit and explicit representations of aqueous solvation, and a p K a value of 14 for the β‐H atom of a model enoxy radical was predicted. Relative to the unactivated β‐H atom of the closed‐shell thioester, this corresponds to an acidity enhancement of over 25 orders of magnitude (see scheme).