A new undergraduate organic chemistry experiment has been developed that features asymmetric synthesis<br/>of an enantioenriched secondary alcohol, followed by determination of the absolute configuration using the competing enantioselective conversion (CEC) method. Students are given a ketone and an unknown enantiomer of CBS catalyst. This reaction forms an enantioenriched secondary alcohol of unknown absolute configuration. The students then assign absolute configuration via the CEC method. The CEC method runs parallel reactions using both enantiomers of a chiral acyl-transfer catalyst, homobenzotetramisole (HBTM). Reactions are quenched at the same time and reaction rates are determined by thin-layer chromatography (TLC) and <sup>1</sup>HNMR. By comparing the faster reaction to a previously determined mnemonic, the absolute configuration of the alcohol can be determined. From this information, the students can then determine which enantiomer of CBS catalyst they used to form the enantioenriched alcohol. This experiment was successfully completed in one 5-hour lab section, with most students finishing in less than three hours. This experiment provides an opportunity for discussion of important chemistry concepts including asymmetric<br/>synthesis, kinetic resolution, mechanism, transition state theory, and inert-atmosphere techniques.

CBS and CEC: Asymmetric synthesis and absolute configuration of an enantioenriched alcohol: A discovery-based undergraduate laboratory experiment

251st National Meeting (2016)

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