A novel chiral ferrocenyl phosphine ligand from sugar: applications in Rh-catalyzed asymmetric hydrogenation reactions

Architecture and synthesis of P,N-heterocyclic phosphine ligands

Diverse P,N-phosphine ligands reported to date have performed exceptionally well as auxiliary ligands in organometallic catalysis. Phosphines bearing 2-pyridyl moieties prominently feature in literature as compared to phosphines with five-membered N-heterocycles. This discussion seeks to paint a broad picture and consolidate different synthetic protocols and techniques for N-heterocyclic phosphine motifs. The introduction provides an account of P,N-phosphine ligands, and their structural and coordination benefits from combining heteroatoms with different basicity in one ligand. The body discusses the synthetic protocols which focus on P–C, P–N-bond formation, substrate and nucleophile types and different N-heterocycle construction strategies. Selected references are given in relation to the applications of the ligands.

Multifunctional chiral phosphine-catalyzed [3+2] annulation of Morita-Baylis-Hillman carbonates with cyclopentenones: asymmetric synthesis of 4-oxo-hexahydropentalenes

A multifunctional chiral phosphine-catalyzed enantioselective [3+2] annulation of Morita-Baylis-Hillman carbonates with cyclopentenones provides a direct approach to access functional 4-oxo-1,3a,4,5,6,6a-hexahydropentalene compounds. Moderate to good yields and excellent enantioselectivities (>90% ee) were obtained for a series of substrates under mild reaction conditions.

Cationic half-sandwich rare-earth metal alkyl species catalyzed polymerization and copolymerization of aryl isocyanides possessing polar, bulky, or chiral substituents

Cationic half-sandwich rare-earth metal alkyl species were first used for the coordination–insertion polymerization and copolymerization of aryl isocyanides.

Lu's [3 + 2] cycloaddition of allenes with electrophiles: discovery, development and synthetic application

The discovery of Lu's [3 + 2] cycloaddition reaction is briefly introduced, and the recent important developments and synthetic applications of Lu's [3 + 2] cycloaddition reaction are highlighted and overviewed.

Ligand and Substrate Effects on the Mechanism of Rhodium-Catalyzed Hydrogenation of Enamides

The rhodium-catalyzed hydrogenation reaction of enamides is studied computationally using the B3LYP/LACVP** level of theory for a range of ligands and substrates. Two model bidentate phosphine ligands, 1,2-bis(dimethylphosphino)ethane (DMPE) and (Z)-1,2-bis(dimethylphosphino) ethene (ZDMP), and two chiral bidentate phosphine ligands, (R,R)-MeDuPHOS and (R,R)-tetramethylbisoxaphospinane (TMBOP), are investigated in the hydrogenation of alpha-formamidoacrylonitrile as a model substrate. The ZDMP ligand is then studied for three additional substrates: N-(2-propenyl)formamide, (Z)-3-formamido-2-butenenitrile, and (E)-3-formamido-2-butenenitrile. The potential-energy surfaces calculated for the four ligands and alpha-formamidoacrylonitrile are in general agreement with previous computational studies using QM/MM (ONIOM) methods but show consistently higher relative barriers rather than lower. The calculated potential-energy surfaces of hydrogenations of various substrates with a common ligand indicate a mechanistic change based on substrate. The sequence of hydrogen transfer to the two olefinic carbons is calculated to change based on substrate electronics. This has a significant impact on the origins of enantioselectivity for such varied substrates as the first hydride transfer to the substrate is calculated to be irreversible for all substrates, independent of whether it occurs at the alpha or beta carbon of the olefin.

C1 and C2-symmetric carbohydrate phosphorus ligands in asymmetric catalysis

Carbohydrates are increasingly used as starting materials for the synthesis of enantiopure ligands. They contain a considerable number of stereocenters, and compounds with all possible configurational combinations are readily available. This tutorial review focuses on ligands obtained by the introduction of phosphorus functionalities (mainly phosphinite, phosphite or phosphine) into a carbohydrate framework. They are classified according to their structural features. In this review, ligands are organised as C1 ligands with a pyranoside or furanoside structure, and C2 ligands. Particular attention is paid to water soluble ligands prepared from carbohydrates. General methods for the preparation of the ligands are presented in order to show how the backbones can be obtained from simple carbohydrates. The catalytic results obtained in commonly studied processes are presented in tables in order to facilitate the comparison between the ligands. The advantages and limitations of the use of ligands based on carbohydrates are discussed.