Most existing ligands for asymmetric catalysis are character. Pchiral functional phosphines by hydrophosphination with. Enantioselective preparation of pchiral phosphine oxides. Synthesis and applications of pchirogenic and axially. The reaction proceeds efficiently with a wide array of. Pdcatalyzed dynamic kinetic enantioselective arylation of. Another approach to the formation of pcbonds is given by the hydrophosphination. Binap is a well known example of a c2symmetric diphosphine which forms chiral complexes due to atropisomerism. If this rate is high, the chiral phosphine has to be temporarily protected pbh 3, ps.
Hydrophosphination with cationic primary phosphine iron complexes. Like nr 3, phosphines have a lone pair on the central atom that can be donated to a metal. Asymmetric catalysis with chiral lewis bases karl scheidt evans group friday seminar march 9, 2001 i. Only a minor part of the chiral phosphines are chiral at the phosphorus atom pstereogenic 79. The products were characterized by 1 h and 31 p nmr measurements. Phosphines are most notable for their remarkable electronic and steric tunability and their innocencethey tend to avoid participating directly in organometallic reactions, but have the ability to profoundly modulate the electronic properties of the metal center to which theyre bound. It is a member of phosphanes, a phosphine and a mononuclear parent hydride. Pchiral monodentate phosphines from hydroxyproline introduction chiral phosphines that possess a stereogenic phosphorous center, while useful, have been challenging to prepare and difficult to handle owing to their susceptibility to aerobic oxidation. Chiral phosphine ligands are categorized into two general classes.
Recent advances in the application of chiral phosphine. Herein we report a remarkable racemization process of three p. The shifts for these chiral molecules, and for a wide range of other phosphines, can be accurately predicted. Nmr studies reveal for the first time that chiral lithium amides can form chelating dimeric complexes with pli interactions in both diethyl ether and thf. However, access to chiral phosphorus ligands is limited due to their challenging synthesis. Pchiral phosphine oxide catalysed reduction of prochiral ketimines using trichlorosilane christopher j. Nucleophilic displacement routes to pchiral phosphines. These compounds are valuable intermediates in the manufacture of not only known. Herein, we present a direct pdxiaophoscatalyzed crosscoupling reaction of easily accessible secondary phosphine oxides and aryl bromides, which provides rapid access to pchiral phosphine oxides. Twelve pchiral phosphine oxides were screened for their ability to act as a chiral lewis base catalyst for the asymmetric hydrosilylation of ketimines, providing chiral amines in. Chiral phosphines are interesting ligands for the preparation of transition metal complex catalysts for asymmetric synthesis 5,6. Treatment of racemic pstereogenic tertiary phosphines with enantiomerically pure bisphosphoryl and bisthiophosphoryl disulfides under kinetic resolution conditions 2.
Preparation of phosphines through c p bond formation. Chiralquest phosphine ligands aldrich chemfiles 2006, 6. Chiral allenecontaining phosphines in asymmetric catalysis. Catalytic synthesis of nonracemic p chiral phosphine derivatives remains a significant challenge. Chiral diphosphines have been particularly popularized. Synthesis and applications of pchirogenic and axially chiral p,n. Professor xumu zhang at penn state has made remarkable advances by creating a toolbox of chiral phosphines which can be used on a variety of substrates, some of which have been historically resistant to hydrogenation. Chiral cage phosphines, european journal of organic. Treatment of racemic p stereogenic tertiary phosphines with enantiomerically pure bisphosphoryl and bisthiophosphoryl disulfides under kinetic resolution conditions 2. Nmr studies of chiral lithium amides with phosphine. The two lithium atoms in the dimer are found to be nonequivalent, one of them is coordinated to two phosphines, detected by 6li,31pcouplings, while the other lithium is only solvent bound. Aryl bromides and chlorides can be coupled to aliphatic and aromatic thiols the widest substrate scope of any reported to date. The epic ligand survey continues with tertiary phosphines, pr 3.
The methodology involves the highly stereoselective formation of p chiral oxazolidinones that then undergo displacement with a variety of grignard reagents to prepare the desired phosphine oxides. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphane p 2 h 4. It has a role as a pesticide and a carcinogenic agent. Synthesis of pchiral phosphine ligands and their applications in. Eight pchiral monodentate ferrocenyl phosphines 1ah were prepared in high enantiomeric excess 95% ee in most cases by way of an ephedrinebased oxazaphospholidine borane complex. Pdf a onestep diastereoselective synthesis of bulky pchiral phosphines with a rigid bicyclic 2. Primary alkyl, secondary alkyl, and substituted aromatic substituents were successfully introduced at the phosphorus center, along with ferrocenyl and phenyl groups, generating phosphines of the general. A highly efficient chiral auxiliarybased strategy for the asymmetric synthesis of p chiral phosphine oxides in 98. The development of transitionmetalcatalyzed methods for the synthesis of pchiral phosphine derivatives poses a considerable challenge. Andersson department of chemical and biological engineering organic chemistry chalmers university of technology abstract this thesis deals with the enantioselective synthesis of chiral mixed phosphorousnitrogen. In chemistry, a molecule or ion is called chiral k a. The requirement of an electronrich chiral phosphine ligand is at the core of this transformation. Kinetic resolution of pchiral tertiary phosphines and.
The better the sigmadonating capability or worse the pi acceptor ability of the other ligands on the metal, the lower the co stretching frequency. Pstereogenic compounds brandon rosen 29 march 2014. Novel substituted diphenyl tertiary phosphines of a pyrrolidine carboxylic acid derivative and their use as catalysts in the enantioselective hydrogenation of. Chiral phosphines in nucleophilic organocatalysis europe. The 31 p nmr chemical shifts have been measured for these phosphines, and show greater deviations from the values predicted by the first order additivity model than do those of more symmetrical phosphines i. Up to here, the reduction of phosphine oxides to phosphines still remains the methods of choice scheme 1. Pchiral, monodentate ferrocenyl phosphines, novel ligands. Enantioselective synthesis of pchiral tertiary phosphine. Chiral phosphines are essential ligands for enantioselective metalcatalyzed reactions. Pchiral phosphines such as dipamp have three different phosphorus substituents. Professor xumu zhang at penn state has made remarkable advances by creating a toolbox of chiral phosphines which can be used on a variety of substrates, some of which have been historically resistant to facile hydrogenation. Seconday phosphines can racemize through acidbase chemistry ipr.
School of physical and mathematical sciences a thesis submitted to the nanyang technological university in fulfillment of the requirement for the degree of. Theymayactasorganocatalysts5b,d as well as precursors to various pchiral phosphine derivatives. Eight p chiral monodentate ferrocenyl phosphines 1a. Tertiary phosphines are generally known to withstand inversion under moderate conditions. The reduction of tertiary and secondary phosphine oxides. A family of pchirogenic phosphine ligands l6 containing a triazole. P chiral, monodentate ferrocenyl phosphines, novel. It is a colorless, flammable, toxic gas and is classed as a pnictogen hydride. Dynamic crystallization processes of pchiral phosphine. Here we report cucatalyzed enantioselective arylation of secondary phosphine oxides with diaryliodonium salts for the synthesis of tertiary phosphine oxides with high enantiomeric excess.
Herein, we present a direct pdxiaophoscatalyzed crosscoupling reaction of easily accessible secondary phosphine oxides and aryl bromides, which provides rapid access to p chiral phosphine oxides. The syntheses of chiral phosphines usually involve expensive procedures, including the use of chiral auxiliaries or the separation of racemic mixtures by resolving methods. Pdf kinetic resolution of pchiral tertiary phosphines. Many chiral phosphine ligands have been produced and utilized for the synthesis of useful optically active compounds. Notably, p chiral phosphines bearing a triazole moiety are unknown, the properties of which are interesting to explore. Herein, we report facile arene ligand exchange reactions of two rutheniumii complexes of tertiary pstereogenic ferrocenyl phosphines. Pchiral phosphines are organophosphorus compounds of the formula prr. A versatile and efficient pdoac 2 1,1bisdiisopropylphosphinoferrocenecatalyzed crosscoupling of thiols with aryl halides was developed.
The new process is demonstrated on a wide range of substrates and leads to products that are wellestablished. This pchiral phosphorus ligand represents a superior. Although pstereogenic phosphines have been known as effective ligands for enantioselective catalysis for over 40 years, 2. The synthesis of novel 3 and 17diphenylphosphinoandrostane derivatives via homogeneous catalytic pc coupling is described. Read nucleophilic displacement routes to pchiral phosphines. Chiral phosphines are essential ligands for asymmetric transitionmetalcatalyzed transformations. Read tertiary phosphines, pchiral phosphinites and phosphonic acid esters bearing fullerene substituent. Enantioselective cucatalyzed arylation of secondary. Metal complexes and redox properties, tetrahedron on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Phosphane is the simplest phosphine, consisting of a single phosphorus atom with three hydrogens attached. Theymayactasorganocatalysts5b,d as well as precursors to various p chiral phosphine derivatives. According to the nmr investigation of the ptcl 2 p 2type complexes, the steroidal phosphines are transcoordinated with respect to the ptcentre exclusively. Reported here is a highly efficient and accelerated catalytic asymmetric synthesis of p.
Facile arene ligand exchange in pcymene rutheniumii. Notably, pchiral phosphines bearing a triazole moiety are unknown, the properties of which are interesting to explore. Enzymatic resolution of chiral phosphinate esters yingchun li, sarah d. Preparation and 31p nuclear magnetic resonance studies of. Asymmetric synthesis of chiral phosphines and arsines promoted by organometallic complexes liu fengli b. New chiral phosphorus ligands for enantioselective hydrogenation wenjun tang and xumu zhang department of chemistry, 152 davey laboratory, the pennsylvania state university, university park, pennsylvania 16802. Development of pchirogenic phosphine ligands based on. Eight pchiral monodentate ferrocenyl phosphines 1a. Pstereogenic compounds brandon rosen 29 march 2014 interconversions between pchiral molecules horner, tet. Our attention was focused on kinetic resolution of pchiral phosphines. The introduction of sterically encumbered groups, journal of organometallic chemistry on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
Pchiral phosphines enabled by palladiumxiaophoscatalyzed. Asymmetric synthesis of chiral phosphines and arsines. Halfsandwich arenemetal complexes are commonly used for specific applications. The development of transitionmetalcatalyzed methods for the synthesis of p chiral phosphine derivatives poses a considerable challenge. Hydrophosphination with cationic primary phosphine iron. By mild photochemical activation, the displacement of pcymene and subsequent tethering by. Chiral quest phosphine ligands in chemical synthesis. These compounds play a pivotal role as ligands and.
New chiral phosphorus ligands for enantioselective. Pchiral phosphine oxide catalysed reduction of prochiral. Synthesis and applications of pchirogenic and axially chiral p,n phosphines as ligands and organocatalysts. The chirality of the phosphine can be attributed either to the organic scaffold or to the phosphorus atom itself pstereogenic or pchirogenic. Accelerated and enantioselective synthesis of a library of.