Asymmetric epoxidation of 2-arylidene-1,3-diketones: facile access to synthetically useful epoxides

Abstract

In this article the first enantioselective epoxidation reaction of acyclic and cyclic 2-arylidene-1,3-diketones is reported. Easily accessible or commercially available alpha,alpha-diaryl prolinols as the organocatalysts in the presence of tert-butyl hydroperoxide (TBHP) provide the corresponding epoxides in high to excellent yield (up to 99%) and up to 85% ee (ee >90% after crystallisation). These epoxides are pharmaceutically important building blocks and intermediates for the synthesis of densely functionalised epoxide derivatives.

One‐Pot Synthesis of Chiral α‐Substituted β,γ‐Epoxy Aldehyde Derivatives through an Asymmetric Aldol Reaction of Chloroacetaldehyde

“…4) A three-component coupling reaction led to the formation of a multifunctional alcohol with excellent enantioselectivity (Table 4). 5) This is one of the rare reactions in which a diarylprolinol is successfully used as an efficient catalyst, [16,19] while its silyl ether is widely used as an effective organocatalyst. [17] Because the generated product possesses several functional groups, this method offers an efficient route for the preparation of chiral a-substituted b,gepoxy aldehydes with excellent diastereoselectivity and enantioselectivity.…”

Chiral N,N′‐Dioxide–Scandium(III)‐Catalyzed Asymmetric Epoxidation of 2‐Arylidene‐1,3‐diketones with Hydrogen Peroxide

“…In 2010, Lattanzi et al. reported the first enantioselective epoxidation of 2‐arylidene‐1,3‐diketones using α,α‐diarylprolinol as organocatalyst and TBHP as oxidant, giving the corresponding epoxides in moderate to good ee values (64–85%) within 3–7 days 10. However, a highly efficient catalytic system for the catalytic asymmetric epoxidation of 2‐arylidene‐1,3‐diketones with environmentally benign H 2 O 2 as oxidant is still desirable.…”

Regioselective aza‐Michael additions of 2‐arylidene‐1,3‐diphenylpropan‐1,3‐diones with isatins: Synthesis of N‐diketone‐functionalized isatins

“…2‐Arylidene‐1,3‐diphenylpropan‐1,3‐diones have many important applications in organic synthesis. [ 8 ] Moreover, they can also be used as acceptors for the Michael additions. [ 9 ] However, to the best of our knowledge, there have been no reports for the aza‐Michael additions with isatins.…”