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Placement of phosphorus in the polymer main chain leads to organophosphorus polymers with potentially unique chemical and physical properties. Here, we demonstrate that the Abramov phosphonylation reaction can be extended to the synthesis of such polymers, by reacting di- or tricarbaldehydes with phosphinic acid (PA) in the presence of N,O-bis(trimethylsilyl)acetamide (BSA). This technique affords polymers with main chain PࣿC bonds, wherein phosphorus(V), aromatic rings, and hydroxymethylene moieties are linked by bis(α-hydroxymethylene)phosphinic acid (BHMPA) units. The resulting polymers are water soluble, display resilience against acid- and base- catalyzed hydrolysis, and exhibit superior thermal stability with high char yield in air (∼83%) and nitrogen (∼76%) atmosphere. This article is protected by copyright. All rights reserved.

Direct catalytic transformation of chlorosilanes into organosilicon compounds remains challenging due to difficulty in cleaving the strong Si-Cl bond(s). We herein report the palladium-catalyzed cross-coupling reaction of chlorosilanes with organoaluminum reagents. A combination of [Pd(C

Sodium exhibits better efficacy and selectivity than Li and K for converting Ph3P(O) to Ph2P(OM). The destiny of PhNa co-generated is disclosed. A series of alkyl halides R4X and aryl halides ArX all react with Ph2P(ONa) to produce the corresponding phosphine oxides in good to excellent yields.

A series of low spin cobalt(I) complexes bearing a tetradentate phenanthroline-based PNNP ligand (2,9-bis((diphenylphosphanyl)methyl)-1,10-phenanthroline), [CoCl(PNNP)] (1), [CoMe(PNNP)] (2) and [Co(CH2SiMe3)(PNNP)] (3), were synthesized and structurally identified. Complex 3 underwent a structural rearrangement of the PNNP skeleton upon heating to form [Co(PNNP′)] (4), which is supported by an asymmetrical PNNP′ ligand with a dearomatized phenanthroline backbone. Mechanistic studies supported that the transformation from 3 to 4 was initiated by the homolysis of either a Co–CH2SiMe3 bond or a benzylic C–H bond. Complex 4 achieved H–H bond cleavage of H2 (1 atm) at ambient temperature, to form [Co(PNNP′′)] (6), in which two H atoms were incorporated into the endocyclic double bond of the PNNP′′ ligand backbone.

The utility of a bipyridine periodic mesoporous organosilica, BPy-PMO, as a support material of a hydrosilylation catalyst was investigated in the hydrosilylation of phenylacetylene with trimethoxysilane. [PtMe2(BPy-PMO)] (1) exhibited a moderate catalytic activity, whereas the reaction was successfully catalysed by [PtMe2(BPy-PMO-TMS)] (2) bearing end-capped TMS groups on the surface. Spectroscopic analyses of 2 revealed that the porous structure of BPy-PMO-TMS remained almost unchanged through the reaction. The hot filtration test supported the nonleaching property of 2, thereby exhibiting good reusability without the loss of the product yields.

A nickel complex/Lewis acid combination effectively catalyzed the direct silyl-Heck reaction of chlorosilanes, which are key raw materials in the organosilicon industry, to give synthetically important alkenylsilane products. Trichlorosilanes, dichlorosilanes, and monochlorosilanes underwent the silyl-Heck reaction to afford the corresponding alkenylsilanes in high yields. In the reactions of dichlorosilanes, a single substitution occurred to give monoalkenylsilanes in a highly selective manner.

Asymmetric desymmetrization was demonstrated by means of transition-metal-catalyzed conjugate reduction with hydrosilanes as reductants. Chiral rhodium-bis(oxazolinyl)phenyl complexes [Rh(Phebox-R)] were found to be effective catalysts for conjugate hydrosilylation of differently γ,γ-disubstituted cyclohexadienones to provide the corresponding product with chiral quaternary centers. The mechanistic consideration was also performed by theoretical calculation. These attempts provided information about i) the initial activation of Rh(III) complex into Rh(I) species assisted by hydrosilanes, ii) the complete catalytic cycle, and iii) an explanation of the asymmetric induction and the difference of the structure of cyclohexadienones in enantioselectivity.

Parahydrogen-induced polarization (PHIP) is a rapid and cost-effective hyperpolarization technique using transition metal-catalysed hydrogenation with parahydrogen. We examined rhodium catalysts and their kinetic studies, rarely considered in the research of current PHIP. It emerged that rhodium complexes with electron-donating bisphosphine ligands, with a dicyclohexylphosphino group, appear to be more effective than conventional rhodium catalysts.

The N,N,O-tridentate chiral phenanthroline ligand was employed for Cu(II)-catalyzed enantioselective α-hydroxylation of β-ketoesters with racemic Davis’ oxaziridine to provide the corresponding product. We also tried to understand the plausible mechanism for asymmetric induction of this reaction, achieved by the effective shielding of prochiral Cu(II) enolate. With this working hypothesis, enantioselective α-chlorination of β-ketoesters to give the corresponding products was achieved with high enantioselectivity.

Nickel(II)-catalyzed enantioselective Michael addition of N-Boc-oxindole derivatives with methyl vinyl ketone was demonstrated to give the corresponding adducts having chiral all-carbon quaternary centers with up to 87% ee in the presence of axially chiral N,N,O-tridentate phenanthroline ligand.

Hydrosilylation of alkenes is an important reaction for the production of organosilicon compounds such as industrially important silicones and silane coupling agents. To synthesize highly sophisticated organosilicon materials, it is of great importance to develop novel hydrosilylation catalysts with good compatibility towards a wide range of functional groups. This review highlights the main advances made in this area. Efforts to develop Pt catalysis systems as well as environmentally benign base-metal catalyst systems have been collected with the aim of providing a comprehensive overview of the subject from the viewpoint of both academia and industry.

Rhodium-catalyzed enantioselective desymmetrizing intramolecular hydrosilylation of symmetrically disubstituted hydrosilanes is described. The original axially chiral phenanthroline ligand (S)-BinThro (Binol-derived phenanthroline) was found to work as an effective chiral catalyst for this transformation. A chiral silicon stereogenic center is one of the chiral motifs gaining much attention in asymmetric syntheses and the present protocol provides cyclic five-membered organosilanes incorporating chiral silicon centers with high enantioselectivities (up to 91 % ee). The putative active Rh(I) catalyst takes the form of an N,N,O-tridentate coordination complex, as determined by several complementary experiments.

Asymmetric diboration of N -acyl-protected allylamines such as substituted imides, amides, and carbamates catalyzed by chiral rhodium[bis(oxazolinyl)phenyl] complexes followed by oxidation in one-pot was realized to produce optically active 3-amino-1,2-propanediol derivatives in high enantioselectivities up to 99%.

Reactions of allyl-functionalized poly(ethylene glycol) (PEG) derivatives with alkoxysilanes proceeded efficiently to furnish the corresponding hydrosilylated products in good to excellent yields using a ruthenium catalyst, [RuCl2(nbd)]n. A preliminary mechanistic study supported the pivotal role of the PEG moiety, which coordinated to the ruthenium atom during the reaction to achieve high reaction selectivity. This method may be applicable to the synthesis of various PEGs with a silyl terminus, which is useful as biocompatible and low toxic silane coupling agents.

Zinc-catalyzed asymmetric α-amination of β-ketocarbonyl compounds 2 using dialkyl azodicarboxylates 3 as the electrophilic nitrogen source is described. The complexes of Zn(OTf)2 and the axially ch...

The novel chiral N,N,O-tridentate ligands (BinThro) containing binaphthyl and phenanthroline units were developed. The enantioselective organozinc addition to aldehydes was performed in the presence of BinThro (S)-1 with up to 95% ee.

Nickel(II)-catalyzed enantioselective Michael addition of N-Boc-oxindole derivatives with methyl vinyl ketone was demonstrated to give the corresponding adducts having chiral all-carbon quaternary centers with up to 87% ee in the presence of axially chiral N,N,O-tridentate phenanthroline ligand.

The N,N,O-tridentate chiral phenanthroline ligand was employed for Cu(II)-catalyzed enantioselective α-hydroxylation of β-ketoesters with racemic Davis’ oxaziridine to provide the corresponding product. We also tried to understand the plausible mechanism for asymmetric induction of this reaction, achieved by the effective shielding of prochiral Cu(II) enolate. With this working hypothesis, enantioselective α-chlorination of β-ketoesters to give the corresponding products was achieved with high enantioselectivity.

The enantioselective desymmetrizing conjugate hydrosilylation of prochiral differently γ,γ-disubstituted cyclohexadienone derivatives 2 to furnish the corresponding cyclohexenones 4 with a remote chiral all-carbon quaternary center at the γ position is described. Chiral rhodium–bis(oxazolinyl)phenyl complexes 1 were effective catalysts for this transformation. This catalytic system was extended to the asymmetric transformation of spirocarbocyclic cyclohexadienones 5 to give the corresponding products 6 with high enantiomeric ratios.

Zinc-catalyzed asymmetric α-amination of various cyclic β-ketocarbonyl compounds using azodicarboxylate (II) as the electrophilic nitrogen source is described.

In the field of asymmetric synthesis, the development of new chiral ligands has been regarded as an attractive challenge for decades. Novel chiral ligands can often have a great impact on synthetic protocols. In this context, we are currently interested in the application of 1,10-phenanthroline (phen) as an entirely new class of chiral ligand. To handle this issue, we designed a chiral phen ligand that provides the N,N,O-tridentate coordination of the phen moiety and an additional phenolic hydroxyl group. As phen possesses greater coordination ability with various ions, our chiral phen ligand would be valuable as one of the "privileged" chiral ligands applied to a broad range of metal catalysts and new reactions. This account summarizes the results of the application of the chiral phen ligand to various kinds of metal catalysis.

In the presence of a Cu(II) complex of axially chiral, N,N,O-tridentate phenanthroline ligand (S)-2, asymmetric oxygen atom transfer of oxindole derivatives (3) using Davis’ oxaziridine (4) occurred to give the corresponding 3-aryl-3-hydroxy-2-oxindole derivatives (1) with excellent enantioselectivity (up to 96% ee). The X-ray crystallographic analysis of the isolated Cu(II) complex disclosed its N,N,O-tridentate coordination, which is critical to realize effective catalytic activity.

Chiral aluminum Lewis acid catalyst composed of Me(3)Al and 3,3'-bis(trimethylsilyl)-BINOL in a 2:1 ratio was found to promote novel catalytic asymmetric ring expansion of cyclohexanone with α-substituted α-diazoacetates to give seven-membered rings with an all-carbon quaternary center. Application of this strategy to 4-substituted cyclohexanones opened up a novel way for the catalytic desymmetrizing asymmetric construction of cycloheptanones bearing remote α,δ-chiral centers.

The enantioselective desymmetrizing conjugate hydrosilylation of prochiral differently γ,γ-disubstituted cyclohexadienone derivatives 2 to furnish the corresponding cyclohexenones 4 with a remote chiral all-carbon quaternary center at the γ position is described. Chiral rhodium–bis(oxazolinyl)phenyl complexes 1 were effective catalysts for this transformation. This catalytic system was extended to the asymmetric transformation of spirocarbocyclic cyclohexadienones 5 to give the corresponding products 6 with high enantiomeric ratios.

Rhodium-catalyzed enantioselective desymmetrizing intramolecular hydrosilylation of symmetrically disubstituted hydrosilanes is described. The original axially chiral phenanthroline ligand (S)-BinThro (Binol-derived phenanthroline) was found to work as an effective chiral catalyst for this transformation. A chiral silicon stereogenic center is one of the chiral motifs gaining much attention in asymmetric syntheses and the present protocol provides cyclic five-membered organosilanes incorporating chiral silicon centers with high enantioselectivities (up to 91 % ee). The putative active RhI catalyst takes the form of an N,N,O-tridentate coordination complex, as determined by several complementary experiments.

In the presence of a Cu(II) complex of axially chiral, N,N,O-tridentate phenanthroline ligand (S)-2, asymmetric oxygen atom transfer of oxindole derivatives (3) using Davis’ oxaziridine (4) occurred to give the corresponding 3-aryl-3-hydroxy-2-oxindole derivatives (1) with excellent enantioselectivity (up to 96% ee). The X-ray crystallographic analysis of the isolated Cu(II) complex disclosed its N,N,O-tridentate coordination, which is critical to realize effective catalytic activity.

The scalable one-pot title reaction allows for the transformation of N-acyl protected amines including imides, amides, and carbamates, bearing a terminal allyl group or, for the first time, a 1,2-substituted E-alkene moiety.

Design of the novel type of axially chiral ligand (BPT) is based on the concept of innovation utilizing phenanthroline units which has superior coordination ability with a wide range of metal ions.

[Structure: see text] A new Brønsted acid-assisted chiral Brønsted (chiral BBA) acid catalyst (1) was developed by substituting a hydroxy group of optically active 1,1'-bi(2-naphthol) with a stronger Brønsted acidic group such as a bis(trifluoromethanesulfonyl)methyl group. The enantioselective Mannich-type reaction of ketene silyl acetals with aldimines catalyzed by (R)-1 in the presence of stoichiometric achiral proton sources gave (S)-beta-amino esters in high yield with moderate to good enantiomeric excesses.

The use of organoaluminum-based Lewis acids (AlRnX3–n; R 1⁄4 alkyl, alkynyl, X 1⁄4 halide or pseudohalide) in the period 2000 to mid-2011 is overviewed with a focus on: (1) stoichiometric reactions in which one of the organoaluminum substituents is transferred to the substrate (e.g., the opening of epoxides, 1,2-additions to carbonyl compounds, coupling with C–X, and Reissert chemistry) and (2) asymmetric, often catalytic, reactions promoted by Lewis acid catalysts derived from organoaluminum species (e.g., use of auxiliaries with alanes, Diels–Alder, and related cycloaddition reactions, additions to aldehydes and ketones, and skeletal rearrangement reactions).

The catalyst controls the process to give seven-membered rings with an all-carbon quaternary center.

Ring expansion of symmetrically substituted cyclohexanones with N-α-diazoacetyl camphorsultam (II) is devised as a stereoselective approach to functionalized cyclic β-keto carbonyls having a kinetically stabilized α-hydrogen.

Ring expansion of symmetrically substituted cyclohexanones with N-alpha-diazoacetyl camphorsultam was devised as a stereoselective pathway to the functionalized 7-membered cyclic beta-keto carbonyls having a kinetically stabilized alpha-hydrogen.

Asymmetric redox C−C bond formation between α-alkyl-α-diazocarbonyl compounds and aldehydes was developed as a practical and general method for the construction of α-alkyl-β-keto imides having a chiral nonracemic tertiary stereogenic center.

Insertion of one methylene unit into the C-C bond of cyclohexanones is a potentially useful, straightforward method for the construction of seven-membered carbocycles. An especially appealing but largely unexplored method in this arena is the nucleophilic addition of diazoalkanes to the Lewis acid-activated cyclohexanones and subsequent ring expansion accompanied by the extrusion of nitrogen (direct Tiffeneau-Demjanov-type ring expansion). Our primary finding is the unprecedented insertion of alpha-alkyldiazoacetates to cyclohexanone and its heteroanalogues, generating seven-membered rings with one all-carbon quaternary center. On the basis of this finding, highly diastereoselective ring expansion of substituted cyclohexanones was developed, furnishing seven-membered rings with 1,4-quaternary-tertiary, 1,4-quaternary-quaternary, or 1,3,5-quaternary-tertiary-tertiary stereogenic centers in a single operation starting from readily available materials. The stereochemical outcome of the product can be easily predicted from the conformation of starting cyclohexanones. Enantioenriched products could be also accessed by the use of (-)-phenylmenthyl alpha-alkyldiazoacetates.

Michael-initiated ring closure of aryldiazoacetates and α-substituted acroleins under acid catalysis offers a unique opportunity for the stereoselective formation of various tetrasubstituted cyclopropanes.

Michael-initiated ring closure of aryldiazoacetates and alpha-substituted acroleins under acid catalysis offers a unique opportunity for the stereoselective formation of various tetrasubstituted cyclopropanes.