Synthesis, Coordination Study, and Catalytic Pauson–Khand Reactions of QuinoxP*(CO)4-μ-Alkyne Dicobalt Complexes

Rhodium-Catalyzed Enantioselective and Desymmetrizative Pauson-Khand Reaction: Access to Tricyclo[6.2.1.04,11]undecenes

Rhodium-catalyzed asymmetric desymmetrization Pauson-Khand reaction of C4-alkynyl-tethered cyclohexadienones has been developed as a novel strategy for access to fused 6-5-5 tricycles bearing three consecutive stereogenic centers. An array of chiral tricyclo[6.2.1.0^4,11]undecenes have been synthesized in high yields and enantioselectivities in a single step under mild conditions. This strategy employs readily accessible internal-olefin-containing 1,6-enynes, providing a potentially powerful tool for constructing chiral polycyclic scaffolds of complex molecules containing cyclopentenones and cyclohexenones.

P-Stereogenic Amino-Phosphines as Chiral Ligands: From Privileged Intermediates to Asymmetric Catalysis

Among chiral phosphines, P-stereogenic phosphines provide unparalleled activity and selectivity and have thus emerged as "state-of-the-art" ligands for asymmetric hydrogenation and other industrially relevant processes. However, the synthesis of this type of ligand implies lengthy multistep sequences, which are a hurdle for many laboratories. There is a lack of methods for the rapid construction of P-stereogenic phosphine ligands. In this respect, P-stereogenic synthons that can be rapidly incorporated into a given ligand scaffold are highly desirable. Over the last 10 years, our group has unveiled that P-stereogenic aminophosphines can be rapidly assembled in a convenient fashion from the corresponding primary aminophosphine and/or the corresponding phosphinous acid.Using cis-1-amino-2-indanol as chiral auxiliary, we devised a multigram synthesis of tert-butylmethylaminophosphine borane and tert-butylmethylphosphinous acid borane, which are key intermediate synthons. Primary aminophosphine works as nucleophilic intermediates at nitrogen. From this synthon, aminodiphosphine (MaxPHOS) and secondary imino phosphoranes (SIP) ligands were synthesized. These ligands exhibit a tautomeric equilibrium between the PH and NH forms, and because of that, they do not undergo oxidation in air. NH/PH tautomerism does not jeopardize their configurational stability, and most importantly, in the presence of a metal source, the equilibrium is shifted toward the NH form, thus allowing coordination through phosphorus. Rh-MaxPHOS and Rh-SIP complexes have been used in asymmetric hydrogenation and [2 + 2 + 2] cycloaddition reactions with outstanding results. On the other hand, P-stereogenic phosphinous acid, upon activation, serves as an electrophilic reagent with amine nucleophiles, allowing S_N2 reactions at phosphorus with complete inversion of configuration. This coupling technology exhibits a great potential because it allows the incorporation of the P*-phosphine fragment in numerous ligand structures, provided there is an amino group with which to react. In a mild and efficient process, phosphinous acid has been coupled to hydrazine to yield C₂ diphosphines and to chiral benzoimidazole-amines to yield P-stereogenic benzoimidazole-phosphine ligands. The most powerful ligand system, however, arises from the condensation of three independent fragments: our phosphinous acid borane, an amino acid, and an amino alcohol, which yields a library of phosphino-oxazoline ligands named MaxPHOX. The corresponding Ir-MaxPHOX catalyst library was applied with excellent results in the asymmetric hydrogenation of α,β-unsaturated esters, 2-aryl allyl phthalimides, unfunctionalized tetrasubstituted alkenes, cyclic enamides, and N-aryl and N-methyl imines. It also has found application in asymmetric isomerization of alkenes.Overall, we developed key P-stereogenic building blocks that can be incorporated stereospecifically to ligand scaffolds and demonstrated that integration of the P*-aminophosphine fragment in a given catalytic system provides structural diversity that can be a critical contribution to obtaining optimal results and selectivity.

Copper(I)-Catalyzed Kinetic Resolution of exo-3-Oxodicyclopentadienes and endo-3-Oxodicyclopentadiene

The first example of highly efficient kinetic resolution of exo-3-oxodicyclopentadienes and endo-3-oxodicyclopentadiene has been developed by means of Cu(I)-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylide. Compared with the existing methodologies for those synthetically important optically active convex molecules, the current protocol provides an alternative but more practical approach from the readily available racemic starting materials, which is free from the repetitive reduction/oxidation steps in the enzymatic resolution or the indispensable stoichiometric amount of chirality-induction reagents.

Norbornene, norbornadiene and their derivatives: promising semi-products for organic synthesis and production of polymeric materials

The methods for synthesis of promising norbornene monomers from norbornadiene and quadricyclane are summarized. A strategy for their synthesis is discussed, combining theoretical and experimental approaches to the selection of catalysts and the conditions for carrying out stereoselective reactions. The mechanisms of catalytic reactions of synthesis of norbornene monomers, as well as the progress in the macromolecular design of functional polymeric materials based on them, are considered. The data on industrial processes of production of polynorbornenes and areas of their use are presented.

The bibliography includes 297 references.