Journal of Organic Chemistry
Journal of Organic Chemistry
5 years ago

Evans Enolates: Structures and Mechanisms Underlying the Aldol Addition of Oxazolidinone-Derived Boron Enolates

Evans Enolates: Structures and Mechanisms Underlying the Aldol Addition of Oxazolidinone-Derived Boron Enolates
Zirong Zhang, David B. Collum
The soft enolization of an acylated oxazolidinone using di-n-butylboron triflate (n-Bu2BOTf) and trialkylamines and subsequent aldol addition was probed structurally and mechanistically using a combination of IR and NMR spectroscopies. None of the species along the reaction coordinate show a penchant for aggregating. Complexation of the acylated oxazolidinone by n-Bu2BOTf was too rapid to monitor, as was the subsequent enolization with Et3N (triethylamine). The preformed n-Bu2BOTf·Et3N complex, displaying muted Lewis acidity and affiliated tractable rates, reveals a rate-limiting complexation via a transition structure with a complicated counterion. n-Bu2BOTf·i-Bu3N bearing a hindered amine shifts the rate-limiting step to proton transfer. Rate studies show that the aldol addition with isobutyraldehyde occurs as proffered by others.

Publisher URL: http://dx.doi.org/10.1021/acs.joc.7b01365

DOI: 10.1021/acs.joc.7b01365

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.