Computational predictions of stereochemistry in asymmetric thiazolium- and triazolium-catalyzed benzoin condensations.
The catalytic asymmetric thiazolium- and triazolium-catalyzed benzoin condensations of aldehydes and ketones were studied with computational methods. Transition-state geometries were optimized by using Morokuma's IMOMO [integrated MO (molecular orbital) + MO method] variation of ONIOM (n-layered integrated molecular orbital method) with a combination of B3LYP/6-31G(d) and AM1 levels of theory, and final transition-state energies were computed with single-point B3LYP/6-31G(d) calculations. Correlations between experiment and theory were found, and the origins of stereoselection were identified. Thiazolium catalysts were predicted to be less selective then triazolium catalysts, a trend also found experimentally.
Dudding
Travis
T
Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA.
Houk
Kendall N
KN
D001573:Benzoin / Q000737:chemistry*; D002384:Catalysis; D008958:Models, Molecular; D015394:Molecular Structure; D013237:Stereoisomerism; D013844:Thiazoles / Q000737:chemistry*; D014230:Triazoles / Q000737:chemistry*
D013844:Thiazoles; D014230:Triazoles; D001573:Benzoin