In this account, two types of chiral phosphinefree ligands, nheterocyclic. Chiral allenecontaining phosphines in asymmetric catalysis. Novel substituted diphenyl tertiary phosphines of a pyrrolidine carboxylic acid derivative and their use as catalysts in the enantioselective hydrogenation of. Professor xumu zhang, chemfiles volume 5 article 4.
We demonstrate that allenes, chiral 1,2dienes, appended with basic functionality can serve as ligandsfortransitionmetals. Tertiary phosphines, pr 3 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. A chiral palladacyclepromoted enantioselective asymmetric hydrophosphination of substituted methylidenemalonate esters using diphenylphosphine that provides direct access to chiral tertiary phosphines is reported. Chiral tertiary phosphines were synthesized by asymmetric hydrophosphination of aromatic enones catalyzed by an organopalladium complex with high yields and stereoselectivity. Recently, enantiomerically pure tertiary phosphine oxides have been obtained using a diasteromerically pure phosphonoamidate based on the backbone of enantiomerically pure sulfonamide 5 as a chiral auxiliary. Pdf in addition to the brilliant chiral phosphorus metal catalysts, chiral phosphinefree metal. Most of these phosphines are acyclic, usually possess low nucleophilic activity, and generally display poor enantioselectivities for phosphine organocatalysis. Enantioselective michael reaction of malonates and chalcones by phasetransfer catalysis using chiral quaternary ammonium salt. Subjected to conventional column chromatography as highly enantioenriched compounds, they greatly experienced racemization when collected at the column outlet within minutes.
Indeed, very little research on chiral tertiary phosphinecatalyzed asymmetric reactions occurred prior to the year 2000 19,20. Catalysis of the michael reaction by tertiary phosphines. Pdf kinetic resolution of pchiral tertiary phosphines. By mild photochemical activation, the displacement of pcymene and subsequent tethering by. Request pdf chiral birch reduced tertiary phosphines. Request pdf kinetic resolution of pchiral tertiary phosphines and chlorophosphines. Pchiral tertiary phosphine oxides are known much longer than their secondary ana logues. Tertiary phosphine complexes of the platinum metals. Synthesis of optically active tertiary phosphine oxides. Palladium ii catalyzed asymmetric hydrophosphination of enones.
Furthermore, because the energy barrier to umbrella flipping of phosphines is quite high, chiralatphosphorus ligands can be isolated in enantioenriched form and introduced to. 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. 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. Cyclic chiral phosphines based on spirocyclic skeletons. Dynamic crystallization processes of pchiral phosphine. We report the highly enantioselective synthesis of pchiral tertiary phosphine oxides featuring an ethynyl group via cuicatalyzed azidealkyne cycloaddition. Chiral phosphapalladacycles as efficient catalysts for the. Pchiral tertiary phosphine to an atom of higher atomic number than 12. Configurationally homogeneous diastereomers of a linear. Our attention was focused on kinetic resolution of pchiral phosphines. This article is from beilstein journal of organic chemistry, volume 10.
Pdf antitumor activity of goldi, silveri and copper. Up to here, the reduction of phosphine oxides to phosphines still remains the methods of choice scheme 1. They are a subset of chiral phosphines, a broader class of compounds where the stereogenic center can reside at sites other than phosphorus. Pdf preparation of phosphines through cp bond formation. Herein, we present a direct pd xiaophoscatalyzed crosscoupling reaction of easily accessible secondary phosphine oxides and aryl bromides, which provides rapid access to pchiral phosphine oxides. Tertiary phosphine an overview sciencedirect topics.
Enantioselective synthesis of pchiral tertiary phosphine oxides with an ethynyl group via cuicatalyzed azidealkyne cycloaddition renyi zhu,a long chen,a xiaosi hu,a feng zhou ab and jian zhou abc we report the highly enantioselective synthesis of pchiral tertiary phosphine oxides featuring an ethynyl. Read diastereoselectivity of the formation of planar chiral ruthenocenol in reactions of chiral tertiary phosphines with the. Diastereoselectivity of the formation of planar chiral. Furthermore, because the energy barrier to umbrella flipping of phosphines is quite high, chiralatphosphorus ligands can be isolated in enantioenriched form and introduced to metal centers, bringing asymmetry. A highly reactive and stereoselective hydrophosphination of enones catalyzed by palladacycles for the synthesis of c and pchiral tertiary phosphines has been developed. The procedure offers practical access to chiral tertiary phosphines. Halfsandwich arenemetal complexes are commonly used for specific applications. Recently chiral phosphines have found very important applications as ligands for the catalysts employed in asymmetric, homogeneous hydrogenation ref. Palladium iicatalyzed asymmetric hydrophosphination of.
The next step involved the regioselective ring opening of 6 occurring with. It is a colorless, flammable, toxic gas and is classed as a pnictogen hydride. Pchiral phosphines are organophosphorus compounds of the formula prr. Efficient access to chiral tertiary phosphines yinhua huang, sumod a. The disclosure provides new and improved methods for the pdcatalyzed asymmetric. Facile arene ligand exchange in pcymene rutheniumii. Platinumcatalyzed asymmetric alkylation of secondary phosphines. Immediately before this use of chiral phosphines, noyori4 had reported the first. Pchirality exploits the high barrier for inversion of phosphines, which ensures that enantiomers of prrr do not racemize readily. These structurally different chiral phosphines can be selected to catalyze. The chiral pt catalyst precursor ptr,rmeduphos ph cl mediated alkylation of racemic secondary phosphines phr r with benzyl halides in the presence of base to give enantioenriched tertiary phosphines pr rch2ar. Chiral tertiary phosphines still occupy a central position in the study of dynamic phosphorus stereochemistry. The reduction of tertiary and secondary phosphine oxides.
Chiral phosphinites bearing a fullerene substituent. Diastereoselectivity of the formation of planar chiral ruthenocenol in reactions of chiral tertiary phosphines with the. The method is applicable to a wide variety of aryl triflate substrates. On the other hand, thousands of arylphosphines have been used as chiral ligands for metalcatalyzed asymmetric reactions 2730. Kinetic resolution of pchiral tertiary phosphines and. Furthermore, because the energy barrier to umbrella flipping of phosphines is quite. The in vitro cytotoxicities of a number of goldi, silveri and copperi complexes containing chiral tertiary phosphine ligands have been examined against the mouse tumour cell lines p815 mastocytoma, b16 melanoma goldi and silveri compounds and p388 leukaemia goldi complexes only with many of the complexes having ic50 values comparable to that of the reference compounds cis. Palladiumiicatalyzed asymmetric hydrophosphination of.
Synthesis and applications of pchirogenic and axially chiral p,n. The epic ligand survey continues with tertiary phosphines, pr3. Pstereogenic compounds brandon rosen 29 march 2014. The following experimentation simply monosubstitutes the readily available triphenylphosphine with a. Wo20282a1 chiral phosphines for palladiumcatalyzed.
Cyclic chiral phosphines based on ferrocene skeletons. Enantioselective synthesis of pchiral tertiary phosphine oxides with. This strategy included in the first step the synthesis of diastereoisomerically pure cyclic oxazaphosphorinane 6. The epic ligand survey continues with tertiary phosphines, pr 3. The first optically active tertiary phosphine oxides were obtained by. Asymmetric nucleophilic catalysis with planarchiral dmap. Treatment of racemic pstereogenic tertiary phosphines with enantiomerically pure bisphosphoryl and bisthiophosphoryl disulfides under kinetic resolution conditions 2. Asymmetric cp bond formation via hydrophosphination. 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. Asymmetric cp bond formation via hydrophosphination activated by palladacycles. The chiral pt catalyst precursor pt r,rmeduphos ph cl mediated alkylation of racemic secondary phosphines phr r with benzyl halides in the presence of base to give enantioenriched tertiary. Palladacyclecatalyzed asymmetric hydrophosphination of.
The reaction proceeds efficiently with a wide array of reaction partners to deliver various tertiary phosphine oxides in up to 96% yield and 97% ee. In this work, a remarkable racemization process of three p. When ph2ph was employed as the hydrophosphinating reagent, a series of cchiral tertiary phosphines were synthesized cp bond formation in high yields with excellent enantioselectivities, and a single. Enantioselective synthesis of p chiral tertiary phosphine oxides with an ethynyl group via cuicatalyzed azidealkyne cycloaddition renyi zhu,a long chen,a xiaosi hu,a feng zhou ab and jian zhou abc we report the highly enantioselective synthesis of p chiral tertiary phosphine oxides featuring an ethynyl. Platinumcatalyzed asymmetric alkylation of secondary. Enantioselective synthesis of pchiral tertiary phosphine. Tertiary phosphines are generally known to withstand inversion under moderate conditions. Kwon chiral phosphines chiral catalysts, ligands, and. Such a prediction prevailed until 1961, when horner2 published a paper, in which he proved that these nonracemic phosphines are stereochemically stable. Many chiral phosphine ligands have been produced and utilized for the synthesis. Chiral phosphines in nucleophilic organocatalysis europe.
Complexes of transition metals with tertiary phosphines and similar complexes with arsines and stibines both nonchelating, for example, c 2 h 5 3 p or chelating, for example, c 6 h 5 2 pch 2 2 pc 6 h 5 2 diphos, have been studied since hofmanns first preparation of triethylphosphine, arsine and stibine platinum and gold complexes in 1857. Electrosynthesis of mixed tertiary phosphines catalysed by nickel complexes complexes of long alkyl chain tertiary phosphines. If this rate is high, the chiral phosphine has to be temporarily protected pbh 3, ps. There are a number of possible synthetic routes to tertiary phosphines with chiral elements, such as inclusion type crystalline complexation, metal complexation and chiral pool synthesis4.
Diversifying reactions of optically active pchiral ethynylphosphine oxides 5273 8. In collaboration with professor ohyun kwon, aldrich chemistry now offers a collection of rigid, chiral 2. The present methods utilize a palladium catalyst supported by new r h 8 binolderived monophosphine ligands. Precursors to asymmetric 1,2cyclohexenebistertiary phosphines the first examples of an optically active birch reduced tertiary. Like nr 3, phosphines have a lone pair on the central atom that can be donated to a metal. Herein, we report facile arene ligand exchange reactions of two rutheniumii complexes of tertiary pstereogenic ferrocenyl phosphines. The in vitro cytotoxicities of a number of goldi, silveri and copperi complexes containing chiral tertiary phosphine ligands have been examined against the mouse tumour cell lines p815 mastocytoma, b16 melanoma goldi and silveri compounds and p388 leukaemia goldi complexes only with many of the complexes having ic 50 values comparable to that of the reference. Antitumor activity of goldi, silveri and copper i complexes containing chiral tertiary phosphines. A new approach to optically active phosphoryl and thiophosphoryl compounds treatment of racemic p. Safer routes to industriallysignificant chiral catalysts bebhinn tullypenon, james t. Tertiary phosphines especially triphenylphosphine react with various compounds giving rise to the formation of alkylidenephosphoranes. Chiral phosphines in nucleophilic organocatalysis beilstein journals. Enantioselective synthesis of pstereogenic phosphines cheminform 2006, 37 29 doi.
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