Jian-Jun Feng

Palladium-Catalyzed Asymmetric Addition of Diarylphosphines to Enones toward the Synthesis of Chiral Phosphines

An asymmetric addition of diarylphosphines to beta-substituted enones under mild conditions using a chiral pincer-palladium catalyst has been developed for the synthesis of chiral phosphines with excellent stereoselectivity (up to 99% ee).

An Atom-Economic Synthesis of Bicyclo[3.1.0]hexanes by Rhodium N-Heterocyclic Carbene-Catalyzed Diastereoselective Tandem Hetero-[5 + 2] Cycloaddition/Claisen Rearrangement Reaction of Vinylic Oxiranes with Alkynes

The first synthetic application of a vinylic oxirane as a heteroatom-containing five-atom component in transition-metal-catalyzed cycloaddition reactions is reported. A new, efficient, diastereoselective tandem intramolecular hetero-[5+2] cycloaddition/Claisen rearrangement of vinylic oxirane-alkyne substrates that uses a rhodium NHC complex and provides strategically novel, atom-economic, regiospecific, and diastereoselective access to [3.1.0] bicyclic products has been developed.

The Divergent Synthesis of Nitrogen Heterocycles by Rhodium(I)-Catalyzed Intermolecular Cycloadditions of Vinyl Aziridines and Alkynes

Catalyst-controlled divergent intermolecular cycloadditions of vinylaziridines with alkynes have been developed. By using [Rh(NBD)2]BF4 as the catalyst, a [3 + 2] cycloaddition reaction was achieved with broad substrate scope and high stereoselectivity under mild reaction conditions. Moreover, the chirality of vinylaziridines can be completely transferred to the [3 + 2] cycloadducts. When the catalyst was changed to [Rh(η(6)-C10H8) (COD)]SbF6, the alternative [5 + 2] cycloadducts were selectively formed under otherwise identical conditions.

Transfer of chirality in the rhodium-catalyzed intramolecular formal hetero-[5 + 2] cycloaddition of vinyl aziridines and alkynes: stereoselective synthesis of fused azepine derivatives.

By taking advantage of vinyl aziridines as a heteroatom-containing five-atom component in rhodium-catalyzed intramolecular formal hetero-[5 + 2] cycloaddition reactions with alkynes, a highly efficient method for the synthesis of fused azepine derivatives at 30 °C was developed. The reaction has broad substrate scope and tolerates a wide range of functional groups. The chirality of vinyl aziridine-alkyne substrates can be completely transferred to the cycloadducts, representing an atom-economic and enantiospecific protocol for the construction of fused 2,5-dihydroazepines for the first time.

Regiodivergent Intermolecular [3+2] Cycloadditions of Vinyl Aziridines and Allenes: Stereospecific Synthesis of Chiral Pyrrolidines

The first rhodium-catalyzed intermolecular [3+2] cycloaddition reaction of vinyl aziridines and allenes for the synthesis of enantioenriched functionalized pyrrolidines was realized. [3+2] cycloaddition with the proximal C=C bond of N-allenamides gave 3-methylene-pyrrolidines in high regio- and diastereoselectivity, whereas, 2-methylene-pyrrolidines were obtained as the major products by the cycloadditions of vinyl aziridines with the distal C=C bond of allenes. Use of readily available starting materials, a broad substrate scope, high selectivity, mild reaction conditions, as well as versatile functionalization of the cycloadducts make this approach very practical and attractive.

Modular Access to the Stereoisomers of Fused Bicyclic Azepines: Rhodium‐Catalyzed Intramolecular Stereospecific Hetero‐[5+2] Cycloaddition of Vinyl Aziridines and Alkenes

The first rhodium-catalyzed intramolecular hetero-[5+2] cycloaddition reaction of vinyl aziridines and alkenes was realized, wherein both internal and terminal alkenes were applicable. With this method, a variety of unique substituted chiral fused bicyclic azepines, bearing multiple contiguous stereogenic centers, were facilely accessed in a straightforward, high-yielding, and highly stereoselective manner under mild reaction conditions. Notably, the E/Z geometry of the CC bonds in the vinyl aziridine-alkene substrates impact the cis/trans stereochemistry of the cycloadducts and up to six stereoisomers could be delivered.

Rhodium(I)-Catalyzed Intermolecular Aza-[4+3] Cycloaddition of Vinyl Aziridines and Dienes: Atom-Economical Synthesis of Enantiomerically Enriched Functionalized Azepines

A new synthetic application of vinyl aziridines as N-containing three-atom components in a rhodium-catalyzed [4+3] cycloaddition reaction is described. The reaction proceeds well with various silyl dienol ethers and vinyl aziridines, and enables the efficient synthesis of highly functionalized azepines in an enantioselective manner with net inversion of absolute configuration. The salient features of the transformation include the use of readily available substrates, high selectivity, and mild reaction conditions, as well as the versatile functionalization of the products.

Transfer of Chirality in the Rhodium-Catalyzed Chemoselective and Regioselective Allylic Alkylation of Hydroxyarenes with Vinyl Aziridines

By taking advantage of chirality-transfer strategy, a chemo- and regioselective allylic alkylation of naphthols and phenols with vinylaziridines provides an atom-economic and efficient method for the synthesis of enantioenriched 2-vinyl-2-arylethylamine derivatives. Use of readily available starting materials, a broad substrate scope, high selectivity, mild reaction conditions, as well as versatile functionalizations of the aromatic ethylamine products make this approach very practical and attractive.

Divergent Access to Functionalized Pyrrolidines and Pyrrolines via Iridium-Catalyzed Domino-Ring-Opening Cyclization of Vinyl Aziridines with β-Ketocarbonyls

A useful synthesis of five-membered N-heterocycles has been developed through an iridium-catalyzed domino-ring-opening cyclization of vinylaziridines with β-ketocarbonyls. α-Substituted 1,3-dicarbonyls reacted with vinylaziridines to give 2-methylenepyrrolidines bearing two adjacent sp3-carbon centers with moderate to excellent diastereoselectivity, while the reaction of α-unsubstituted 1,3-dicarbonyls afforded 2-pyrrolines in good yield.

Chirality Transfer in Rhodium(I)-Catalyzed [3 + 2]-Cycloaddition of Vinyl Aziridines and Oxime Ethers: Atom-Economical Synthesis of Chiral Imidazolidines

A highly efficient and stereoselective synthesis of enantioenriched imidazolidines by rhodium-catalyzed intermolecular [3 + 2] cycloaddition reaction of chiral vinyl aziridines and oxime ethers has been successfully developed. Notably, both aldoximes and ketoximes are suitable substrates to afford the corresponding chiral imidazolidines in high yields with good stereoselectivity. This transformation represents an unprecedented example that utilizes ketimine derivatives as an aza-[2C]-component in cycloadditions of vinyl aziridines.