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

Abstract

Rhodium-catalyzed C(sp )-H functionalization reactions of 4-aryl-5-pyrazolones followed by [3+2] annulation reactions with alkynes provide rapid access to highly enantioenriched five-membered-ring 4-spiro-5-pyrazolones. The use of a chiral SCpRh catalyst enabled the synthesis of a large range of spiropyrazolones with all-carbon quaternary stereogenic centers in up to 99 % yield and 98 % ee from readily available substrates.

Catalytic Asymmetric Synthesis of Spiropyrazolones and their Application in Medicinal Chemistry

“…In 2017, You and co‐workers conducted an Rh‐catalyzed asymmetric C−H functionalization/annulation process between 4‐aryl‐5‐pyrazolones 94 and alkynes 17 , thereby providing access to a spiro[pyrazolone‐indane] scaffold 95 (Scheme ) . A BINOL‐derived Cp*Rh complex and several SCpRh catalysts were screened, and Cat.…”

Synthetic Routes towards Multifunctional Cyclopentadienes

“…[28] Youa nd co-workers first reported spiro-bisinden-derived Cps in 2015 (VI), whereas Antonchick and Waldmann described the preparation of piperidine-fused Cps in 2017( VII). [29] Most of these Cps are used as ligands for transition-metal complexes (mainly Rh and Ir) which are highly efficient and versatile catalysts. For detailed structures, synthetic routes and applicationso ft hese ligands, the readeri sr eferred to the several reviews that have already been published in the field.…”

Rhodium(III)‐Catalyzed Direct C7 Allylation of Indolines via Sequential C−H and C−C Activation

“…[16] As useful organic synthons, vinylcyclopropanes (VCPs) can undergo ring-opening reactions, cycloadditions, and rearrangements in synthetic chemistry. [19] In recent years, we have achieved Rh-catalyzed enantioselective allylation, alkynylation, and CÀH cyanation. [18] Rhodium complexes have been recognized as effective catalysts for multiple transformations.…”