Regiodivergent Synthesis of Oxadiazocines <i>via </i>Dirhodium-Catalyzed Reactivity of Oxazolidines and <i>α</i>-Imino Carbenes

Using electron-rich or electron-poor N-substituted oxazolidines as substrates, selective formation of either ammonium or oxonium ylides is possible in the presence of α-imino carbenes. As such, treatment of 5-membered oxazolidine precursors with N-sulfonyl-1,2,3-triazoles under dirhodium catalysis (2 mol%) affords the regiodivergent synthesis of either 8-membered 1,3,6- or 1,4,6-oxadiazocines upon the initial N or O reactivity with the carbene.</p

Regiodivergent Synthesis of Oxadiazocines via Dirhodium-Catalyzed Reactivity of Oxazolidines and alpha-Imino Carbenes

AbstractUsing electron-rich or electron-poor N-substituted oxazolidines as substrates, selective formation of either nitrogen or oxygen ylides is possible in the presence of alpha-imino carbenes. As such, treatment of 5-membered oxazolidine precursors with N-sulfonyl-1,2,3-triazoles under dirhodium catalysis (2 mol%) afford the regiodivergent synthesis of either 8-membered 1,3,6- or 1,4,6-oxadiazocines upon the initial N- or O-reactivity with the carbene

Dataset of Regiodivergent Synthesis of Pyrazino-Indolines vs. Triazocines via α-Imino Carbenes Addition to Imidazolidines

AbstractHexahydropyrazinoindoles were prepared in a single step from N-sulfonyl triazoles and imidazolidines. Under dirhodium catalysis, α-imino carbenes were generated and formed nitrogen ylide intermediates that, after subsequent aminal opening, afforded the pyrazinoindoles predominantly via formal [1,2]-Stevens and tandem Friedel-Crafts cyclizations. Of mechanistic importance, a regiodivergent reactivity was engineered through the use of a specific unsymmetrically substituted imidazolidine that promoted the exclusive formation of 8-membered ring 1,3,6-triazocines. Based on first principles, an original Curtin-Hammett-like situation was demonstrated for the mechanism. Further derivatizations lead to functionalized tetrahydropyrazinoindoles in high yield

Diversity-oriented synthesis of heterocycles and macrocycles by controlled reactions of oxetanes with α-iminocarbenes.

Using N-sulfonyl triazoles as substrates, compounds as diverse as 2-imino tetrahydrofurans, 13- and 15-membered ring aza-macrocycles can be prepared selectively via formal [1 + 4], [5 + 4 + 4] and [3 + 4 + 4 + 4] condensations of α-imino carbenes and oxetanes under Rh(ii)-catalysis or thermal activation. Spirocyclic N-heterocycles are also accessible by means of Buchwald-Hartwig and Pictet-Spengler cyclizations. By reaction control, substrate selection or further derivatization, a large variety of chemical structures is thus achievable. Finally, using triazoles reacting under thermal activation, interesting mechanistic insight was obtained