SCpRh(III)‐Catalyzed Enantioselective Aryl C−H Addition to Nitroalkenes

Abstract

Rh-catalyzed enantioselective direct addition of benzamide CÀ H bond to nitroalkenes was developed. In the presence of chiral SCpRh(III) catalyst, an array of CÀ H adducts was obtained in moderate to excellent yields and enantioselectivity (57-92% yields, 71-92% ee) under mild conditions. The reaction conditions accommodate a wide range of diverse functional groups.

Transition-metal-catalyzed C–H bond alkylation using olefins: recent advances and mechanistic aspects

“…Subsequently, You and co-workers developed an ( S )-CpRh catalyst based on a chiral 1,1′-spirobiindane scaffold to increase the enantioselectivity of the particular reaction. 77 They were able to gain yields and enantioselectivity up to 92%. Utilizing similar Rh-catalyzed diastereoselective hydroarylation of d -glucose-derived nitroalkene 22e and a late-stage intramolecular transamidation strategy, the Ellman group achieved the concise total synthesis of (+)-pancratistatin in a 10-step linear sequence from readily available starting materials (Scheme 22B).…”

Rhodium-Catalyzed Asymmetric C–H Functionalization Reactions

“…In 2017, Ellman and co-workers described a Cp x Rh complex Rh-2p catalyzed asymmetric hydroarylation of nitroalkenes 217 (up to 73% yield, 82% ee, Scheme a) . Later in 2021, a new catalytic system involving [SCpRh] Rh-5c was reported by You and co-workers, which could enhance both yield and enantioselectivity of the reaction (up to 92% yield, 92% ee, Scheme b) . Very recently, a class of BCSCpRh-complexes were designed by You and co-workers, which led to comparable results in the asymmetric synthesis of 218 (up to 88% yield, 98% ee) .…”

“…167 Later in 2021, a new catalytic system involving [SCpRh] Rh-5c was reported by You and co-workers, which could enhance both yield and enantioselectivity of the reaction (up to 92% yield, 92% ee, Scheme 34b). 168 Very recently, a class of BCSCpRh-complexes were designed by You and co-workers, which led to comparable results in the asymmetric synthesis of 218 (up to 88% yield, 98% ee). 169 In 2021, Li and co-workers used N-aryl maleimide 220 as the electrophile, and diverse amides 221 bearing both C−N axial and central chirality were synthesized in good yields, diastereoand enantioselectivities (up to 98% yield, >19:1 dr and >99% ee, Scheme 34c).…”

Synthesis of Hexamethyl-1,1′-spirobiindane-Based Chiral Spiro Cp Ligands and Their Application in Rhodium-Catalyzed Enantioselective Aryl C–H Addition to Nitroalkenes

“…1,1′-Spirobiindane has been recognized as a privileged chiral scaffold to provide an excellent platform for chiral ligand and catalyst diversification since the pioneering work of Zhou. − In 2016, our group designed and synthesized a series of 1,1′-spirobiindane-derived Cp (SCp) ligands and successfully applied their Rh complexes in an asymmetric oxidative coupling reaction . Since then, application of SCpRh in versatile catalytic asymmetric C–H functionalization reactions has been well demonstrated. − Despite their successful applications in challenging C–H functionalization reactions, these SCp ligands are synthetically less practical due to the tedious synthesis and relatively expensive SPINOL starting material. Therefore, the design of novel SCp ligands with practical synthesis is of great significance and in high demand.…”

“…Then, the utility of these newly developed BCSCpRh complexes in asymmetric C−H functionalization was explored. Recently, we reported a Rh-catalyzed enantioselective direct addition of aryl C−H bond to nitroalkenes, 53 and the highest enantioselectivity for the reaction of pyrrolidine benzamide 6a with nitrostyrene 7a could only reach 86% ee in the presence of the optimized catalyst Rh-9. Furthermore, the ee values of the products are generally lower than 90%.…”