A reactivity/affinity switch for parallel kinetic resolution: alpha-amino acid quasienantiomers and the resolution of cyclopropene carboxylic acids.
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.
Liao
Lian-an
LA
Brown Laboratories, Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
Zhang
Fan
F
Dmitrenko
Olga
O
Bach
Robert D
RD
Fox
Joseph M
JM
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
D000596:Amino Acids; D002264:Carboxylic Acids; D003521:Cyclopropanes; C021985:cyclopropene