Rhodium-Catalyzed 3-Aza-Cope Rearrangement of Protic N-Allyl Enammonium Ylides Enabled by Resonance Assisted H-Bonding

31 July 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Herein, we present the design of a new class of Rh-bound protic N-allyl enammonium ylides and its stereoselective 3-aza-Cope rearrangement. These transient ylides are generated in situ by the Rh-catalyzed reaction of vinyldiazo com-pounds and N-secondary-(Z)--enamino carbonyl compounds, under mild conditions. Mechanistic studies revealed that the resonance-assisted hydrogen bonding (RAHB) of protic enammonium ylide promotes exclusively [3,3] rear-rangement by disfavouring both 1,2-proton transfer (NH-insertion) and direct carbenoid C-C bond formation. This new reaction was used in the synthesis of multi-substituted pyrroles, dihydropyrroles, deuterated pyrroles, tetrahy-droindoles, and pyrroloindole scaffold of an antitumor and UV-protecting agent terreusinone.

Keywords

Carbenoid
diazoenal
3-aza-Cope
protic N-allyl enammonium ylide
pyrrole

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