One-Pot Conversion of <i>N</i>‑Allyl-α-cyano Esters to α‑Allyl-α-cyano Lactams through a Hydrolysis/Ketene Formation/Cyclization/Claisen Rearrangement Sequence

An intramolecular ketene aza-Claisen rearrangement is developed for the first time to enable the stereoselective synthesis of α-ally-α-cyano-lactams from <i>N</i>-allyl amino esters. This reaction also exhibits outstanding chemoselectivity when an unsymmetrical bis-<i>N</i>-allyl group is present in the starting molecule. The usefulness of this method is demonstrated by a short synthesis of optically active bicyclolactam from l-proline

The Reaction of 2,3-Dimethylimidazole-1-sulfonyl Azide Triflate with 3‑Substituted Indoles: Reactivity and Scope

2,3-Dimethylimidazole-1-sulfonyl azide triflate reacts with 3-substituted indoles to deliver 2-iminoindolines, 2-aminoindoles, or 2-imino-3-aminoindolines by using different conditions. This imidazolium sulfonyl azide shows higher reactivity toward carbon nucleophile indoles than ordinary alkyl/aryl sulfonyl azides

Stereoselective Construction of Bridged <i>trans</i>-aza-Bicyclo­[7/6,3/2,1]­alkenyl Imines through Ring Expansion aza-Cope Rearrangement

A highly stereoselective method for efficient synthesis of unprecedented bridged bicyclo­[7/6,3/2,1]­alkenyl amidines is described using cyclic <i>N</i>-allyl-aminoalkyne as a substrate. A ketenimine formation/cyclization/aza-Cope rearrangement cascade proceeds either with or without the aid of external DIPEA depending on substrate basicity. Fused bicycloamidines are also obtained via the same protocol using different <i>N</i>-allyl cyclic aminoalkynes

One-Pot Protocol to Functionalized Benzopyrrolizidine Catalyzed Successively by Rh₂(OAc)₄ and Cu(OTf)₂: A Transition Metal–Lewis Acid Catalysis Relay

4-<i>N</i>-Allylarylpropylamino-1-sulfonyl triazoles are converted to structurally unique benzopyrrolizidinyl sulfonamides in a one-pot operation. Intramolecular capture of rhodium carbene with arylamino nitrogen gives rise to the formation of an ammonium ylide immediate. A [2,3]- or [1,2]-rearrangement occurs to give a 2-allylpyrrolidinyl-2-carbimine intermediate which undergoes Cu­(OTf)₂ catalyzed aza-Friedel–Crafts cyclization to finish a highly functionalized tricyclic system decorated with a synthetically difficult quaternary carbon center, a sulfonamide group, and an allyl segment

Copper-Catalyzed Borylative Cyclization of Substituted <i>N</i>‑(2-Vinylaryl)benzaldimines

A <i>t-</i>BuOCu-initiated reaction sequence of styrene borometalation and intramolecular imine addition has been achieved using a Cu­(OTf)₂/dppf combination as catalyst. The product of this reaction cascade is a useful 2,3-disubstituted indoline bearing a versatile boryl moiety and is formed with sole <i>cis</i>-selectivity. To account for the observation of the exclusive formation of <i>cis</i>-stereoisomers, a transition state featuring copper–imine coordination is suggested. The application to the synthesis of antioxidant tetrahydroindenoindoles is described

Rhodium-Catalyzed Chemo- and Regioselective Cross-Dimerization of Two Terminal Alkynes

Cross-dimerization of terminal arylacetylenes and terminal propargylic alcohols/amides has been achieved in the presence of a rhodium catalyst. This method features high chemo- and regioselectivities rendering convenient and atom economical access to functionalized enynes