Elucidating the Mechanism of Reversible Oxiranations via Magnetization Transfer Spectroscopy

作者：Chase Daniel T; Moerdyk Jonathan P; Bielawski Christopher W^*

来源：Organic Letters, 2012, 14(21): 5510-5513.

DOI：10.1021/ol302596r

The reversible [2 + 1] cycloadditions between an N,N%26apos;-diamidocarbene (DAC) and eight aldehydes were examined using NMR spectroscopy. Variable temperature magnetization transfer experiments revealed higher exchange rates and lower activation barriers when electron-deficient aldehydes were employed. Likewise, competitive equilibrium studies indicated a thermodynamic preference for electron-deficient aryl and sterically unhindered alkyl aldehydes compared to more electron-rich or bulkier substrates. Collectively, these and other data collected were consistent with the oxiranation process proceeding in an asynchronous manner.

• 出版日期2012-11-2