Bisphosphine oxide

The Wittig-Horner procedure, starting from bisphosphonate or aromatic bisphosphine oxide monomers, allows for AA/BB-coupling of the PO-activated bismethylene monomers, not only with aromatic dialdehydes but also with aromatic diketones to the corresponding PPV derivatives (76), and for the selfcondensation of AB-type aromatic starting compounds containing both alde-hyde/keto and PO-activated methylene functions [101]. 

By using three equivalents of diphenylphosphine oxide (relative to al-kyne), the palladium-catalyzed reaction affords bisphosphine oxides in high... 

Bidentate oxygen-donor extractants include the neutral diamide compounds, such as the malonamides used in the French DIAMEX and DIAMEX-SANEX processes, RR N(C=0)-CHR"-(C=0)NRR the bisphosphine oxides, RR (P=0)- CIIR"-(P=0) RR the carbamoyl-(methyl)-phosphinates, R0R 0(P=0)-(CI I On o 0rr(C=0)NRR or the more efficient carbamoyl-methyl-phosphine oxides, RR (P=0)-CHR"-(C=0)... 

Chiral bisphosphine oxides were stereoselectively reduced to chiral trans- and cis-bisphosphines that can be useful ligands in catalytic asymmetric hydrogenation67. When 73 was treated with benzaldehyde, it gave a cyclized alcohol 74 and its diastereoisomer 75 in 54% and 8% isolated yields, respectively (Scheme 25)68. 

It was recently reported that, upon treatment with lithium diisopropylamide, achiral and chiral a,/3,, conjugate addition-tandem-cyclization to 172 to afford the corresponding endo-a,fi-unsaturated cyclic bisphosphine oxides, 173 (Scheme 53)115. 

The synthesis of bisphosphine oxides, e.g. (24), has attracted attention in this year s literature. > The object of much of this work is the application of... 

The synthesis and X-ray crystal structure of the macrocyclic bisphosphine oxide manganese complex (75) have been reported. A stable P-bonded phosphinidene oxide complex (77) of rhenium (1) has been prepared from (76) by nitrogen replacement with C-tertiarybutylphosphaalkyne followed by hydrolysis. 1 X-Ray crystallography was used to determine the structure of (77). What is reported to be the first complex (78) with a PO ligand has been prepared. 2 The molecular structure of (78), determined by X-ray crystallography, shows an exceptionally short PP distance. 

Aluminium-BINOL-based complexes have also been shown to be highly selective bifunctional asymmetric cyanation catalysts. For example the bisphosphine oxide (6.65) developed by Shibasaki and coworkers catalyses the cyanation of both aromatic and aliphatic aldehydes with ees ranging from 83-98%. ... 

The apphcation of the rhodinm(l)-catalyzed double [2+2+2] cycloaddition approach to the synthesis of symmetric biaryl diphosphoms compounds was first accomplished in the reactions of l,4-bis(diphenylphosphinoyl)bnta-l,3-diyne with terminal diynes to give achiral biaryl bisphosphine oxides [23a]. Cj-Symmetric axially chiral biaryl diphosphonates were obtained with perfect enantioselectivity by using a phosphonate-substituted 1,3-bntadiyne and internal 1,6-diynes (Scheme 21.19) [23b]. Axially chiral biaryl dicarboxylates were also obtained by this method [23b]. 

The intramolecular [2+2+2] cycloaddition of triynes affords tricyclic compounds, which are not readily accessible by other methods. The double [2+2+2] cycloaddition of a diphenylphosphinoyl-substituted hexayne proceeded in the presence of the cationic rhodium(I)/tol-BINAP catalyst to give the corresponding Cj-symmetric axially chiral biaryl bisphosphine oxide with high enantioselectivity (Scheme 21.24) [28]. 

Use of the rhodium(I)-catalyzed double [2- -2-1-2] cycloaddition approach to the synthesis of symmetric biaryl diphosphorus compounds was first reported by Doherty et al. The reactions of l,4-bis(diphenylphosphinoyl)buta-l,3-diyne 81 with terminal a,co-diynes 80 proceeded at room temperature in the presence of the cationic rhodium(I)/BINAP catalyst to give symmetric biaryl bisphosphine oxides 82 in excellent yields (Scheme 9.29) [27]. Subsequent reduction of bisphosphine oxide 82 furnished the corresponding bisphosphine 83 (Scheme 9.29) [27]. 

Allen A Jr, Ma L, Lin W (2002) Lacile synthesis of chelating bisphosphine oxides and bisphosphines via palladium-catalyzed bishydrophosphinylation reactions. Tetrahedron Lett 43 3707-3710... 

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