Rhodium/Copper‐Catalyzed Annulation of Benzimides with Internal Alkynes: Indenone Synthesis through Sequential CH and CN Cleavage

Abstract

An zwei Stellen gebrochen: Ein Rhodium(III)‐Kupfer(II)‐System katalysiert die Anellierung von Benzimiden mit internen Alkinen unter Bildung von Indenonen (siehe Schema; Cp*=C5Me5). Die Reaktion umfasst die ungewöhnliche nukleophile Addition einer Übergangsmetall‐Kohlenstoff‐Bindung an eine Imideinheit. Dieser neuartige Prozess ermöglicht die Synthese von Indenonen aus leicht zugänglichen Ausgangsverbindungen.

Transition-Metal-Catalyzed C–H Bond Addition to Carbonyls, Imines, and Related Polarized π Bonds

“…184 After an extensive screen of different amides, the activated N -acyl oxazolidinone was found to be the most effective for directing Rh(III)-catalyzed concerted-metallation-deprotonation and addition to an alkyne while simultaneously providing the acidic oxazolidinone leaving group upon cyclization. A number of substituted N -benzoyl oxazolidinones 332 were investigated.…”

Synthesis of Symmetric and Unsymmetric Secondary Amines from the Ligand-Promoted Ruthenium-Catalyzed Deaminative Coupling Reaction of Primary Amines

“…7 Selective catalytic C–C coupling methods via sp 3 C–N bond activation of allyl- and benzylic amines have been achieved. 8 Other notable examples of catalytic C–N bond cleavage reactions include: oxidative C–H coupling reaction of amides with alkynes, 9 and Milstein group’s report on the Ru-catalyzed hydrogenolysis of amides. 10 Catalytic C–N cleavage methods have also been successfully utilized for constructing nitrogen heterocycles.…”

Asymmetric Synthesis of Spiropyrazolones by Rhodium‐Catalyzed C(sp2)−H Functionalization/Annulation Reactions

“…[6] In recent years,t he direct functionalization of inert C À H bonds has been recognized as an effective way to construct stereogenic centers owing to the rapid development of suitable chiral catalysts and ligands. [10] Very recently,w e reported the synthesis of an ew class of chiral Cp ligands (SCp) based on the privileged 1,1'-spirobiindane scaffold, and their rhodium complexes (SCpRh) were found to be excellent catalysts for the synthesis of axially chiral biaryl compounds. [8] The C 2 -symmetric chiral Cp x Rh complexes,i np articular,h ave found broad applications in asymmetric catalysis.…”

“…[9] Notably, Lam and co-workers reported an elegant Rh III -catalyzed asymmetric synthesis of spiroindenes by C À Hf unctionalization and spiroannulation with alkynes. [10] Very recently,w e reported the synthesis of an ew class of chiral Cp ligands (SCp) based on the privileged 1,1'-spirobiindane scaffold, and their rhodium complexes (SCpRh) were found to be excellent catalysts for the synthesis of axially chiral biaryl compounds. [11] In line with our interest in asymmetric C À H functionalization processes,w ee nvisioned that five-membered-ring 4-spiro-5-pyrazolones could be obtained in an enantioselective fashion by Rh-catalyzed CÀHfunctionalization of 4-aryl-5-pyrazolones and subsequent annulation with alkynes (Scheme 1d).…”