title: Origin of stereoselectivity in a chiral N-heterocyclic carbene-catalyzed desymmetrization of substituted cyclohexyl 1,3-diketones.
abstract: The mechanism and stereoselectivity in a chiral N-heterocyclic carbene-catalyzed desymmetrization of a 1,3-diketone is established by using density functional theory computations. The Breslow intermediate formation is identified to involve Hunig's base-assisted proton transfer. The relative energies of stereoselectivity-determining intramolecular aldol cyclization transition states reveal that in the most preferred mode the re-face of enolate adds to the si-face of carbonyl leading to a tricyclic lactone with a configuration (2aS,4aS,8'S) in excellent agreement with previous experimental reports.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
authors.forename: Yernaidu
authors.initials: Y
authors.lastname: Reddi
authors.forename: Raghavan B
authors.initials: RB
authors.lastname: Sunoj