Merging strain-release and copper catalysis: the selective ring-opening cross-coupling of 1,2-oxazetidines with boronic acids

Decarboxylative Aminomethylation of Indole-3-carboxylic Acids via Strain Release-Driven Ring Opening of 1,2-Oxazetidines

A copper-catalyzed decarboxylative aminomethylation of indole-3-carboxylic acids with 1,2-oxazetidines has been developed, enabling the rapid synthesis of structurally diverse 3-aminomethylindoles in good to excellent yields. Remarkably, an unprecedented decarboxylative aminomethylation/cyclization cascade was further achieved by a combination of copper and iron salts to construct complex γ-carbolines with high efficiency. It is worth noting that one of the obtained products proved to be a good dual-emissive luminogen, exhibiting both aggregation-caused quenching and aggregation-induced emission.

Ficini Reaction with Acrylates for the Stereoselective Synthesis of Aminocyclobutanes

The first Ficini reaction between ynamides and acrylates is reported herein. The reaction is catalyzed by B(C6F5)3 acting as a Lewis acid and is giving access to stable tri-substituted aminocyclobutenes in high yield. The resulting products can be hydrogenated and epimerized under basic conditions or in presence of a Lewis acid, providing two distinct trans- aminocyclobutane monoester stereoisomers in high yield and diastereoisomeric ratio (up to quantitative yield and >99 : 1 dr).

Synthesis of 1,2-oxazetidines with a free -NH group via photoredox catalysis

A photoredox approach enabling one-step synthesis of oxazetidines with a free -NH group via the combined use of alkyne, thiophenol, and azide has been reported. The synthesized oxazetidine with the free -NH group was stable enough for various late-stage transformations such as methylation, acetylation, tosylation, and ring-opening reaction to afford synthetically useful α-aminoketones.