Hydroformylation of styrene in the presence of platinum(II) complex catalysts incorporating cyclic phosphines and phosphonous diesters as P-ligands

The hydroformylation activity of various 5- and 6-membered P-heterocycles was investigated in platinum-catalysed hydroformylation of styrene. All of the tested ligands, such as the phosphole-, oxaphosphorine- and phoshinine-based ligands proved to be catalytically active. Especially good aldehyde selectivities were obtained with the chelating diphenylphosphino-tetrahydrophosphinine and diphenylphosphino-hexahydrophosphinine ligands. While the two aldehyde regioisomers were formed close to equimolar amounts with the monodentate ligands, high branched selectivities were observed with the chelating ones. The effect of the 4-substitution of the parent styrene on chemo- and regioselectivity was investigated.     

4-(p-Methylthio)phenyl-2,6-diphenyl phosphinine: The first X-ray crystal structure of a λ3-triaryl-phosphabenzene

The new donor functionalized methylthio-phosphabenzene 3 was synthesized by reaction of the corresponding pyrylium salt with P(SiMe₃)₃. This compound was characterized crystallographically, showing eight independent molecules in the asymmetric unit. 3 crystallized in the orthorhombic space group Pna2₁ (no. 33) with cell parameters a=48.3565(8) ?, b=7.64784(7) ?, c=40.8432(4) ?, V=15104.7(3) ?³. This result represents the first crystal structure analysis of a λ³-triaryl-phosphabenzene.     

2,4,6‐Tri(hydroxy)‐1,3,5‐triphosphinine,P3C3(OH)3: The Phosphorus Analogue of Cyanuric Acid

Cyanuric acid (C₃H₃N₃O₃) is widely used as cross‐linker in basic polymers (often in combination with other crosslinking agents like melamine) but also finds application in more sophisticated materials such as in supramolecular assemblies and molecular sheets. The unknown phosphorus analogue of cyanuric acid, P₃C₃(OH)₃, may become an equally useful building block for phosphorus‐based polymers or materials which have unique properties. ¹ Herein we describe a straightforward synthesis of 2,4,6‐tri(hydroxy)‐1,3,5‐triphosphinine and its derivatives P₃C₃(OR)₃ which have been applied as strong π‐acceptor η⁶‐ligands in piano stool Mo(CO)₃ complexes.     

Synthetic studies on a series of functionalized pyrylium salts, 4-chloro- and 4-bromophosphinines

A series of new pyrylium salts that bear sulfonate and phosphonate groups were obtained from the reactions between 2,6-diphenyl-4H-pyran-4-one, sulfonic anhydride, and chlorophosphates, and analyzed spectroscopically. Furthermore, treatment of 2,6-diphenyl-4H-pyran-4-one with phosphoryl chloride or bromide afforded the corresponding 4-chloro- and 4-bromopyrylium tetrafluoroborates in good yield. Subsequently, the synthesis of the corresponding 4-chloro- and 4-bromophosphinines was accomplished by treating the respective chloro- and bromopyrylium tetrafluoroborates with tris(trimethylsilyl)phosphine.     

Synthesis of phosphinines and phosphinanes using zirconium chemistry

Ring expansion of readily available zirconacyclopentadienes or zirconacyclopentanes by insertion of chloro(trimethylsilyl)methyllithium followed by metathesis with phosphorous trichloride provides a novel route to λ³-phosphinines (phosphabenzenes) or phosphinanes.