Bis- phosphine oxide

The bis(dioxolanyl)oxazolidinone 33 has been prepared from D-mannitol and evaluated as a chiral auxiliary <02MT749> and the diamine 34 has been examined as a ligand for rhodium catalysed asymmetric hydrogenation of diethyl itaconate <02JOU104>. Deracemisation of 2-benzylcyclohexanone by formation of an inclusion complex with the TADDOL compound 35 has been described and the mechanism clarified by X-ray structure determination of the complex <02T3401>. A production process for the bis(phosphine oxide) 36 has been patented <02USP6472539>. 

In one of the few examples of a chiral ligand-controlled asymmetric reaction mediated by Sml2, Mikami reported the use of the chiral, bis-phosphine oxide, BINAPO (4), as a Lewis basic additive.23 For example, reductive coupling of methyl acrylate and acetophenone using Sml2 in THF with 2 equiv of BINAPO gave lactone 5 in 46% yield and 67% ee (Scheme 2.8).23... 

SCHEME 12.1 Chemical structures of widely used Pis and their abbreviations. IRG with a number stands for Ciba s designation of a PI Irgacure 2959, etc. DAR stands for Ciba s Darocur 1173 TPO stands for Lucerin TPO of BASF or Darocur TPO of Ciba BAPO stands for bis-phosphine oxide or Irgacure 819 of Ciba. 

The reactions proceed with retention of configuration at phosphorus. Various classical routes to alkylphosphine oxides have been applied in the synthesis of a range of potentially chelating and pincer-like ligands, e.g., (233), the binaphthyl system (234), the hybrid phosphine oxide-N-oxide (235), and the chiral pyridine bis(phosphine oxide) (236). A route to diarylmethylphosphine oxides is afforded by the palladium-catalysed reaction of aryl bromides with tet-rakis(hydroxymethyl)phosphonium chloride in the presence of a base. The diastereoisomeric system (237) has been isolated from the reaction of a cyclic... 

Structural and Physical Aspects. - The stability of the various conformers of the phosphines oxides (269)- 211) has received theoretical consideration. A new triclinic polymorph of triphenylphosphine sulfide has been structurally characterised, together with a related triclinic polymorph of triphenylphos-phine. Two reports of the solid state crystal structure of the phenolic phosphine oxide (272) have appeared. A crystallographic study has confirmed that the product of electrochemical oxidation of o-diphenylphosphinoben-zenethiol is the disulfide-bridged bis(phosphine oxide) (273). Solid-state structural studies of the dioxides (274), the (i )-(-I-)-isomer of (275), 1-hexynyl(diphenyl)phosphine oxide,tribenzylphosphine oxide, and tris(t-butyl)phosphine selenide," have also been reported. 

The bis(phosphine oxide) (48) was useful in the synthesis of 3-diphenylphos-phinsulfido-tetrahydrophosphinine sulfide (51) in which the same kind of intramolecular interactions found in the analogous dioxide derivative could be established (Scheme 23) [34],... 

Phosphine Chalcogenides as Ligands. - The enhanced stability provided by two triphenylphosphine oxide ligands has enabled the first crystal structure analysis of a non-haem-di-iron-dioxygen adduct. Complexes of the bis(phosphine oxide) (213 Z=0) with copper(I) and copper(II), and of the related disulfide (213 Z=S) with gold(I) and silver(I), have been characterised. 

BINAP is not derived from a natural product, and has to be synthesized in the laboratory and resolved using a naturally derived resolving agent. The scheme shows one method by which enantiomerically pure BINAP may be made—the resolution step is unusual because it relies on formation of a molecular complex, not a salt. The bis phosphine oxide of (5)-BINAP co-crystallizes with di-Obenzoyl-L-tartrate, leaving the (fi)-phosphine oxide in solution. Base releases the pure (ff)-phosphine oxide that is resolved, which is then reduced to the phosphine with trichlorosilane. 

A bis(phosphine oxide) was synthesized by C-phosphorylation via metallation (Scheme 18). ... 

The phosphine-catalyzed umpolung y-addition of diphenylphosphine oxide to diphenylphosphinoyl-methylacetylene was accomplished best under MW conditions in isopropanol. The bis(phosphine oxide) was obtained in 72% yield The reaction was extended also to other model compounds, but in these cases another isomer was also formed. The unsaturation of the primary products was removed by catalytic hydrogenation (Scheme 21) ... 

GiUieany et al. [71-76] reported the oxidation of tertiary phosphine 133 with polyhaloalkanes in the presence of chiral proton-donating auxiliary L-menthol (the asymmetric Appel reaction). As a result, chiral phosphine oxides 134 were prepared with good enantiomeric excess. The latter were then treated with LDA and copper chloride to afford the bis-phosphine oxide which is a useful chiral ligand for asymmetric catalysis. The chiral bis-phosphine oxide R,R)-liS was produced in 98% ee and the minor amount of meso-isomer formed was easily removed by recrystallization from benzene, which yielded enantiopure (>99.9% ee) bis-phosphine oxide 135 in an isolated yield of 73% from the racemic phosphine 133 (Scheme 41). 

A ternary soft Lewis-acid/hard Bronsted-base/hard Lewis-base catalytic system for the direct catal5rtic enantioselective addition of allyl cyanide 37 to ketones to give tertiary alcohols with a Z-olefin (38) has been developed by Shibasaki (Scheme 2.24). Mechanistic studies revealed that Cu(i)/chiral phosphine ligand 35 and Li(OC6H4-p-OMe) serve as a soft Lewis acid and a hard Bronsted base, respectively, allowing for deprotonative activation of 37 as the rate-determining step. The hard Lewis base, bis(phosphine oxide) 36,... 

Leung et al. described titanium(rv) terminal hydroxo complexes containing chelating bis(phosphine oxide) ligands, such as BINAPO. The metal ion extracting ability of mainly a-keto-phosphine oxides and related compounds (Fig. 4) based on complex formation has been investigated by quantum chemical calculations. ... 

A cationic acetylplatinum complex with a hydroxy group-containing diphosphine 163 is obtained from the reaction of bis(phosphine oxide) with a Pt(ii) complex, and this complex is readily hydrolyzed to give neutral chloro complex 164 (Scheme 28)7 ... 

Acetonitrile was converted to bis(diphenylphosphino)acetonitrile, that gave the bis(phosphine oxide or sulphide) on treatment with hydrogen peroxide or elemental sulphur (Scheme 4). ... 

Enantiomerically pure Norphos derivatives were synthesized and used as chiral bisphosphine ligands for the catalyst system Pd(dba)3 CHCI3/ PhC02H in the intramolecular hydroamination of aminoalkynes. The synthetic approach to the racemic bis(phosphine oxide) precursor of Methyl Norphos is shown in Scheme 7. ... 

Tetraaryl bis(phosphine oxides) were prepared as shown in Scheme 8. The last step involved Sonogashira cross-coupling. The products included symmetrical and asymmetrical bis(phosphine oxides) (Schemes 8-1 and 8-2, respectively). ... 

The synthesis of bifunctional 2,6-bis(oxazolyl)pyridine (pybox) ligands including bis(phosphine oxides) was also reported (Scheme 9). °... 

Bis(phosphine oxides) can be selectively reduced to bis(phosphine) monoxides under exceptionally mild conditions using triflic anhydride and a thiol. An example is represented by Scheme 11. ... 

A bis(phosphine oxide) served as a co-ligand in a tetrazolate-based Eu(m) complex (Fig. 2). ... 

Bis(phosphine oxide)-functionalized crown ethers were synthesized by the cyclization of 2,2 -dihydroxy-6,6 -bis(diphenylphosphinoxido-)biphenyl and a series of polyethyleneglycol-type ditosylates (Scheme 58). ... 

The precursor of a new atropisomeric bis(phosphine oxide) derivative was synthesized from l-bromo-3-(trifluoromethoxy)benzene via P-functionalization, coupling and optical resolution (Scheme 16). ... 

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