title: A reactivity/affinity switch for parallel kinetic resolution: alpha-amino acid quasienantiomers and the resolution of cyclopropene carboxylic acids.
abstract: A new type of parallel kinetic resolution (PKR) is reported in which quasienantiomers with very similar reactivities give products whose chromatographic properties diverge upon the addition of fluoride. This concept of a reactivity/affinity switch is applied to the PKR of cyclopropene carboxylic acids with all-carbon quaternary centers. This is the first application of alpha-amino acid quasienantiomers in PKR, and it is a complementary approach for acyltransfer systems where the asymmetry is induced by the nucleophile rather than the leaving group. Excellent diastereoselectivities (ranging from 90:10 to 99.5:5) and good yields were obtained for both quasienantiomeric products, and the reactions can be run on significant scale because the separation is trivial. High-level DFT calculations (B3LYP functional with the 6-31+G(d,p) basis set) provided transition-state structures with relative energies that are in accord with the experimental observations.
authors.affiliation: Brown Laboratories, Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
authors.forename: Lian-an
authors.initials: LA
authors.lastname: Liao
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.forename: Olga
authors.initials: O
authors.lastname: Dmitrenko
authors.forename: Robert D
authors.initials: RD
authors.lastname: Bach
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Fox
mesh_terms: D000596:Amino Acids / Q000138:chemical synthesis / Q000737:chemistry*; D002264:Carboxylic Acids / Q000138:chemical synthesis / Q000737:chemistry*; D003521:Cyclopropanes / Q000138:chemical synthesis / Q000737:chemistry*; D007700:Kinetics; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D000596:Amino Acids; D002264:Carboxylic Acids; D003521:Cyclopropanes; C021985:cyclopropene