Carbonyl coordination chemistry from a new angle: a computational study of alpha-carbon acidity based on electrophile coordination geometry.
[reaction: see text] The dependence of acidity on Li+ coordination geometry to alpha-carbon acids is investigated by generating potential energy surfaces of Li+ complexation with acetaldehyde and its respective enolate. The global minimum for the enolate complex shows significant Li+-pi-system coordination to both oxygen and the alpha-carbon. The gas-phase acidity analysis reveals significantly more alpha-carbon coordination, which presumably enhances the lability of the cleaving proton in the transition state of deprotonation.
Houk
Ronald J T
RJ
Department of Chemistry and Biochemistry, A5300, The University of Texas at Austin, Austin, Texas 78731, USA.
Anslyn
Eric V
EV
Stanton
John F
JF
D002244:Carbon / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008094:Lithium / Q000737:chemistry; D008956:Models, Chemical; D008968:Molecular Conformation; D013816:Thermodynamics
D002244:Carbon; D008094:Lithium