A palladium-catalyzed ortho-acylation of tertiary benzamides using arylglyoxylic acids has been described. Unlike the palladium insertion reported to occur in the distorted N–C(O) amide bond of tertiary benzamides, the current study unveils ortho C–H palladation in acylic or cyclic N , N -dialkylbenzamides affording ortho-acylated tertiary benzamides in good to excellent yields. Our experimental study on the mechanism provides information on the tendency of the amide nitrogen toward weak coordination with palladium as opposed to oxygen. However, density functional theory calculations suggest coordination of amide oxygen to palladium, which makes the mechanism especially interesting. A Pd(II)/Pd(III) catalytic cycle and nucleophilic attack by the acyl radical rather than arylglyoxylate anion are supported by mechanistic studies.

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1,3‐Dipolar cycloaddition between nonstabilized azomethine ylides and N‐sulfonylimines has been developed, providing practical access to mono‐N‐sulfonylimidazolidines. The enhanced reactivity of N‐sulfonylimines as dipolarophiles towards azomethine ylides largely eliminated possible Michael addition and favored 1,3‐dipolar cycloaddition. Our approach could complement commonly practiced strategies for protection of imidazolidines. Furthermore, nucleophile‐dependent ring cleavage of N‐sulfonylimidazolidines produced synthetically useful mono‐N‐sulfonyl‐1,2‐diamines, which are otherwise difficult to obtain. Ring cleavage accompanied by CH2 extrusion, yielding mono‐N‐sulfonyl‐1,2‐diamines, occurred on treatment with TBAF, whereas N‐methylated derivatives of N‐sulfonyl‐1,2‐diamines were produced on treatment with LAH.

Die Nitronsäuresilylester (II) (die vorteilhaft in situ aus den entsprechenden Nitroverbindungen und Trimethyl‐silylchlorid dargestellt werden) addieren die Olefine (I) unter Bildung der Isoxazolidine (III), die in Gegenwart von Tos‐OH in die Isoxazoline (IV) übergehen.