Catalytic Metallonitrene/Alkyne Metathesis: A Powerful Cascade Process for the Synthesis of Nitrogen-Containing Molecules

Abstract

A conceptually novel metallonitrene/alkyne metathesis cascade reaction has been developed for the construction of nitrogen-containing compounds from simple alkyne starting materials. Rhodium(II) tetracarboxylate salts are efficient catalysts for this reaction, in which an electrophilic rhodium nitrene is trapped by an alkyne, resulting in the formation of a new C-N bond and the generation of a reactive metallocarbene for cascade reaction. The reaction is tolerant of both alkyl and aryl substituents on the alkyne, and proceeds at room temperature in a variety of common solvents. The modular nature of the reaction allows for the rapid construction of congested bicyclic systems from remarkably simple alkyne starting materials.

A manganese catalyst for highly reactive yet chemoselective intramolecular C(sp3)–H amination

“…Although chemoselective propargylic C—H amination with carbamates to furnish 1,2-amino alcohols is precedented 35 , amination using sulfamate esters to afford the 1,3-amino alcohol motif is challenging as the alkyne typically undergoes alternate oxidation pathways 36 . Instead, two-step sequences have been developed that involve amination of activated ethereal C—H bonds to furnish N,O -acetals followed by Lewis acid-promoted alkylations to generate propargylic amines 1 .…”

Toward a Symphony of Reactivity: Cascades Involving Catalysis and Sigmatropic Rearrangements

“…[160] Thus, treatment of simple linear sulfamate ester ( 441 ) with phenyl iodonium acetate and a rhodium(II) catalyst followed by reductive workup provided good yields of bicyclic oxathiaze-panes ( 447 , Scheme 96). The sequence is believed to proceed by alkyne attack on an electrophile rhodium nitrene leading potentially to a vinyl cation that isomerizes to an imine metallocarbene ( 443 ).…”

Intermolecular and Selective Synthesis of 2,4,5‐Trisubstituted Oxazoles by a Gold‐Catalyzed Formal [3+2] Cycloaddition

“…[1] Following the formation of a-oxo/imido organogold species by intramolecular atomtransfer processes onto alkynes, [2,3] such intermediates [Eq. [1] Following the formation of a-oxo/imido organogold species by intramolecular atomtransfer processes onto alkynes, [2,3] such intermediates [Eq.…”