Stereoconvergent Direct Ring Expansion of Cyclopropyl Ketones to Cyclopentanones

Recyclization of the ring-opening species of alkyl cyclopropyl ketones to cyclopentanones, which proceeds through an unfavored 5-endo-trig cyclization predicted by Baldwin’s rules, is elusive. Herein, as assisted by a strong aryl donor and the Thorpe–Ingold strain on a quaternary cyclopropyl center, stereoconvergent direct ring expansion of cyclopropyl ketones to cyclopentanones promoted by TfOH or BF3·Et2O is described, providing a modular construction of polysubstituted cyclopentanones from aldehydes, alkyl methyl ketones, and α-keto esters within three steps

Highly Enantioselective Nickel-Catalyzed Oxa-[3+3]-annulation of Phenols with Benzylidene Pyruvates for Chiral Chromans

Nickel-catalyzed asymmetric annulation of oxygenated phenols and previously challenging 3-aminophenols with β,γ-unsaturated α-ketoesters is described, leading to rapid access to a variety of oxygenated and 7-aminated chromans in excellent yields with excellent diastereoselectivities and enantioselectivities under mild conditions. This method was readily scaled-up to gram scale and applied for a concise synthesis of two potential anticancer agents 7-aminated 4-arylchromans

Synergetic Tandem Enantiomeric Enrichment in Catalytic Asymmetric Multi-Component Reactions (AMCRs): Highly Enantioselective Construction of Tetracyclic Indolines with Four Continuous Stereocenters

Tetracyclic indolines are ubiquitous skeletons in bioactive natural products and pharmaceuticals, and efficient methods for their enantioselective synthesis are highly desired. Here, we report an efficient three-component formal [2 + 2 + 2] cycloaddition reaction between indoles, 2,3-dihydropyran, and methylene malonates for rapid construction of optically active tetracyclic indolines bearing four continuous stereocenters. Although the optimal catalyst Cu­(II)/BOX displays only moderate enantioselectivities in either formal cyclobutanation or [4 + 2] cycloaddition reaction with donor–acceptor cyclobutanes bearing a nonracemizable stereocenter, the collaborative tandem enantiomeric enrichment in the one-pot asymmetric multicomponent reaction is highly effective, thereby affording a wide range of tetracyclic indoline derivatives with excellent diastereo- and enantioselectivities in high yields

Synergetic Tandem Enantiomeric Enrichment in Catalytic Asymmetric Multi-Component Reactions (AMCRs): Highly Enantioselective Construction of Tetracyclic Indolines with Four Continuous Stereocenters

Tetracyclic indolines are ubiquitous skeletons in bioactive natural products and pharmaceuticals, and efficient methods for their enantioselective synthesis are highly desired. Here, we report an efficient three-component formal [2 + 2 + 2] cycloaddition reaction between indoles, 2,3-dihydropyran, and methylene malonates for rapid construction of optically active tetracyclic indolines bearing four continuous stereocenters. Although the optimal catalyst Cu­(II)/BOX displays only moderate enantioselectivities in either formal cyclobutanation or [4 + 2] cycloaddition reaction with donor–acceptor cyclobutanes bearing a nonracemizable stereocenter, the collaborative tandem enantiomeric enrichment in the one-pot asymmetric multicomponent reaction is highly effective, thereby affording a wide range of tetracyclic indoline derivatives with excellent diastereo- and enantioselectivities in high yields

Synergetic Tandem Enantiomeric Enrichment in Catalytic Asymmetric Multi-Component Reactions (AMCRs): Highly Enantioselective Construction of Tetracyclic Indolines with Four Continuous Stereocenters

Tetracyclic indolines are ubiquitous skeletons in bioactive natural products and pharmaceuticals, and efficient methods for their enantioselective synthesis are highly desired. Here, we report an efficient three-component formal [2 + 2 + 2] cycloaddition reaction between indoles, 2,3-dihydropyran, and methylene malonates for rapid construction of optically active tetracyclic indolines bearing four continuous stereocenters. Although the optimal catalyst Cu­(II)/BOX displays only moderate enantioselectivities in either formal cyclobutanation or [4 + 2] cycloaddition reaction with donor–acceptor cyclobutanes bearing a nonracemizable stereocenter, the collaborative tandem enantiomeric enrichment in the one-pot asymmetric multicomponent reaction is highly effective, thereby affording a wide range of tetracyclic indoline derivatives with excellent diastereo- and enantioselectivities in high yields

Synergetic Tandem Enantiomeric Enrichment in Catalytic Asymmetric Multi-Component Reactions (AMCRs): Highly Enantioselective Construction of Tetracyclic Indolines with Four Continuous Stereocenters

Tetracyclic indolines are ubiquitous skeletons in bioactive natural products and pharmaceuticals, and efficient methods for their enantioselective synthesis are highly desired. Here, we report an efficient three-component formal [2 + 2 + 2] cycloaddition reaction between indoles, 2,3-dihydropyran, and methylene malonates for rapid construction of optically active tetracyclic indolines bearing four continuous stereocenters. Although the optimal catalyst Cu­(II)/BOX displays only moderate enantioselectivities in either formal cyclobutanation or [4 + 2] cycloaddition reaction with donor–acceptor cyclobutanes bearing a nonracemizable stereocenter, the collaborative tandem enantiomeric enrichment in the one-pot asymmetric multicomponent reaction is highly effective, thereby affording a wide range of tetracyclic indoline derivatives with excellent diastereo- and enantioselectivities in high yields