Reactivity of Oxazol-5-(4H)-ones and Their Application toward Natural Product Synthesis

Abstract

This work reviews the reactivity of oxazolones and their application in the synthesis of natural products. In particular, the focus is on the development and scope of oxazolone-mediated enetype reactions, 1,3-dipolar cycloadditions, and a novel Claisen-type rearrangement. The utility of these reactions towards natural product synthesis is described.

Theoretical Study on the Epimerization of Azlactone Rings: Keto–Enol Tautomerism or Base-Mediated Racemization?

“…1,2 The versatility of these compounds is related to the presence of different reactive sites, bearing both electrophilic and pronucleophilic moieties, thus allowing its use in the stereoselective synthesis of α,α-amino acids, complex heterocycles, and natural products. 3,4 An important aspect concerning these cycles is the presence of an acidic hydrogen (p K a ≈ 9), which is attributed to the aromatic character of its enol tautomer. 5,6…”

Highly diastereo- and enantioselective C2 addition of 5H-oxazol-4-ones to γ-keto-α,β-unsaturated esters

“…1 As 5 H -oxazol-4-one compounds are easily accessible and versatile synthons, the functionalization of azlactones has gained widespread interest from chemists. 2 The well-established protocols involve Michael addition, 3 the aldol reaction, 4 the Mannich reaction, 5 cycloaddition, 6 nucleophilic substitution, 7 as well as oxidative cross-coupling. 8 However, these studies have mainly focused on the C4-site of the azlactone.…”