Correction to "dynamic Kinetic Resolution of α-Keto Esters via Asymmetric Transfer Hydrogenation"

Full text of DOI:10.1021/jacs.5b00787

Addition/Correction
pubs.acs.org/JACS
Correction to “Dynamic Kinetic Resolution of α‑Keto Esters via
Asymmetric Transfer Hydrogenation”
Kimberly M. Steward, Emily C. Gentry, and Jeffrey S. Johnson*
J. Am. Chem. Soc. 2012, 134, 7329−7332. DOI: 10.1021/ja3027136
In follow-up experiments in our laboratory, we have found that
1
errors in analyzing the unpurified H NMR spectra led us to
incorrectly report the crude diastereomer ratios for the lactone
products. The correct ratios are listed below. To address this
issue, we have developed an alternative experimental procedure
that generally results in improved stereoselectivity. The
reduction is conducted at room temperature, and then the
reaction mixture is warmed to 70 °C to achieve lactonization.
For example, in an aggregate of two trials, lactone 2a was
obtained in 84% yield, >30:1 dr, and 95:5 er when the
reduction was conducted at ambient temperature for 24 h,
followed by heating for 16 h at 70 °C. Lactone 2d was similarly
prepared in 98% yield (dr >30:1 dr, er 95:5, two runs). Using
α-keto ester 1h as a substrate, the major diastereomer of
lactone 2h was isolated in 78% yield (crude dr = 7:1, er 95:5,
two runs) using this updated procedure. We regret the error
and suggest using this revised protocol for optimal results. The
authors thank Blane Zavesky and Guy Goodman of these
laboratories for their work on the revised protocol.
Published: March 9, 2015
© 2015 American Chemical Society
3715
DOI: 10.1021/jacs.5b00787
J. Am. Chem. Soc. 2015, 137, 3715−3715