Achiral counterion control of enantioselectivity in a Bronsted acid-catalyzed iodolactonization.

ABSTRACT: Highly enantioselective halolactonizations have been developed that employ a chiral proton catalyst-N-iodosuccinimide (NIS) reagent system in which the Brønsted acid is used at catalyst loadings as low as 1 mol %. An approach that modulates the achiral counterion (equimolar to the neutral chiral ligand-proton complex present at low catalyst loadings) to optimize the enantioselection is documented for the first time in this transformation. In this way, unsaturated carboxylic acids are converted to ?-lactones in high yields (up to 98% ee) using commercially available NIS.

SUBMITTER: Dobish MC 

PROVIDER: S-EPMC3326820 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature