Enantioselective catalysis by small organic molecules, or organocatalysis, is an increasingly popular strategy in asymmetric synthesis due to its operational simplicity and inexpensive, mild reagents. The development of new organocatalytic synthetic methodologies is made difficult, however, by a lack of understanding of their reaction mechanisms. We employ density functional theory to study organocatalyst conformational and mechanistic behavior to aid in catalyst and methodology design. Our current work examines the use of a quinine-derived organocatalyst to convert an abundant, biorenewable, achiral feedstock - citric acid - into a valuable chiral synthon. Results thus far include identifying the major conformers of the organocatalyst and the key enantioselectivity-determining transition states. An important conclusion from these results is that the key acyl-transfer step in the reaction appears to proceed by a concerted mechanism rather than the tetrahedral-intermediate-based mechanism hypothesized in the literature. Future work will focus on identifying screening new organocatalysts and substrates to optimize the enantioselectivity of this reaction.

Organocatalysts for biorenewable desymmetrization

245th National Meeting (2013)

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