Tris phosphanes

In the group of Izod, the tris(phosphane oxide) 19 was 1,2-dilithiated by the reaction with two equivalents of w-butyllithium in THF at room temperature (Scheme 7). The similarity of the structural formula of compound 20 (Lewis formula) to 1,2-dilithium compounds found by Sekiguchi and coworkers (see Section n. E), where two lithium centres are bridging a C2 unit, is not maintained in the solid state. The X-ray structural analysis reveals a centrosymmetric dimer containing no carbon-lithium contacts (Figure 8). 

All the reported methods suffer from drawbacks, being either multistep processes that are time-consuming or affording difficult-to-separate mixtures of bis- and tris(phosphane) complexes.13 Moreover, they usually require an excess of phosphane or the cumbersome preparation of sophisticated starting materials, ultimately leading to low overall yields. It is noteworthy that the tris(phosphine) complexes cannot be prepared by substitution of CO by phosphine in the well-known and easily prepared bis(phosphine) complexes.14... 

We also had a good test for efficiency, since all we had to do was run rotation measurements on an appropriately diluted reaction mixture. Our job was to find a phosphane of the appropriate structure. Early on we tried phosphanes with a chiral alkyl side chain, and the asymmetric bias was barely detectable. We felt strongly that, if one wanted to obtain high ee values, the asymmetry would have to be directly on the phosphorus. That is where the action is. 

Fig. 20.9 [PhB(CH2PPh2)3CoI] is a rare example of a low-spin, distorted tetrahedral complex. The tripodal tris(phosphane) is a strong-field ligand.

Tlie desulfurization of thiono compounds is another frequently used synthetic approach for the formation of double bonds via carbenoid intermediates. By this methodology, some indigoid 1,3,5,7-tetraazafulvalenes 88 and 90 were synthesized (83BSB781 90JPR949).Tliis dimerization starting from 2,4,5-tris(dimethylamino)imidazolium chloride via the appropriate thione 87 has been realized in the presence of phosphanes or phosphites to... 

Attempts to prepare 2-butoxy-3//-azepines by heating nitro compounds with tris(di-ethylamino)phosphane in /m-butyl alcohol failed, as diethylamine, liberated by alcoholysis of the aminophosphane, reacts in preference with the alcohol (vide supra) to give the Ar,/V-di-ethyl-3//-azepin-2-amine in good yield.176 However, the deoxygenation of nitroarenes with tributylphosphane in the presence of primary and secondary alcohols furnishes 2-alkoxy-3//-azepines 98 in practicable yields.79... 

Die Reduktion von 1-Chlor-l-nitro-2 bzw. 1-Chlor-l-nitroso-cycloalkanen3 durch Tri-phenyl-phosphan kann zur Herstellung von Lactamen verwendet werden z.B. ... 

Equation (3) shows that when tri(2-pyridyl)phosphane 9 [44] is treated directly with trimethyl aluminum in diethyl ether the adduct complex Me3Al(/r-Py)PPy2 10 is obtained which has structurally been characterised,... 

This chapter will also deal with compounds containing two or three phosphinous amide units, which, for simpUcity, will be named here as bis(amino-phosphanes) or tris(aminophosphanes) but not with phosphinous amides containing other additional organophosphorus functionaUties as, for instance, the so-called aminophosphine phosphinites (AMMP), which have been the subject of increasing attention in the Uterature dealing with catalytic asymmetric transformations and have been treated in other reviews [2,3]. 

OS 41a] ]R 19] ]P 30] Ten different substrates (C4-C8 alcohols) were reacted with rhodium(I)-tris(fn-sulfophenyl)phosphane [110]. The variance in conversions (ranging from about 1-62%) determined was explained by differences in the solubility of the alcohols in the aqueous catalytic layer and by their different intrinsic activities. Chain length and steric/electronic effects of the different alcohols affected their reactivity in a well-known pattern (Figure 4.63). The results obtained correspond to the conversions achieved in a well-mixed traditional batch reactor (40 cm ). They further agreed with data from mono-phasic processing. 

OS 41a] [R 19] ]P 30] A study was undertaken to compare extended (1 h) processing in small vials (2 cm ) with short-time (100 s) continuous micro reactor and mini-batch (10 cm ) operation for 10 different substrates (C4-C8 alcohols) which were reacted with rhodium(I)-tris(m-sulfophenyl)phosphane [111]. The vials were either directly filled with the two phases yielding a bilayered fluid system with small specific interfaces or by interdigital micro mixer action yielding an emulsion with large specific interfaces. 

RIJQEG0 (Tris(N-morpholyl)phosphane-selenide)iodine(I) triiodide di-iodine 2.590 3.186 172.01 AA... 

In fact, tris(pyrrolidino)phosphane oxide has a donor number of 1.22. 

Starting from acylated 2-azidomethylbenzimidazoles (145), an additional imidazole ring can be condensed by transformation of the azido group with tri-n-butylphosphane into the appropriate iminophosphorane intermediate 146. After extrusion of phosphane oxide, cyclization occurs to the 1-substituted 4//-imidazo[l,5-a]benzimidazole 147 (Scheme 58) (89T1823 94S1197). 

The main products under all variations of R and R are the P2-chlorinated triphosphanes. Side reactions such as SiMe3/Cl exchange, P—P cleavage by LiP(SiMe3)R, or transmetallations take place only to a small extent. MeP(SiMe3)2 is an exception inasmuch as it reacts with P-chlorinated phosphanes to yield tri- and even tetraphosphanes. 

When phosphaalkynes are exposed to bis- and tris(diazo) compounds, bis- or tris(l,2,4-diazaphosphol-5-yl) compounds are formed that may be further converted into a variety of novel heterocyclic systems. For example, bis- and tris[diazo(tri-methylsilyl)methyl]phosphanes 237 and 240 afforded bis- and tris(diazaphospho-lyl)phosphanes 238 and 241 after cycloaddition with terf-butylphosphaacetylene followed by a subsequent 1,5-silyl shift (Scheme 8.56) (300). Reaction with electrophilic halides at the Wsilyl functions allows the introduction of a heteroatom bridge between the diazaphosphole ring leading to polycyclic ring systems such as 239 and 242. 

Durch Wittig-Olefinierung lassen sich 1-Nitromethyl-cycloalkene mit Triphenyl- oder Tri-butyl-phosphan in Gegenwart von Tetrakis-[triphenylphosphan]-palladium(0) und an-schlieBender Basen-katalysierter Reaktion mit Aldehyden in einer Eintopfreaktion zu 1 -(1-Alkenyl)-cycloalkenen ( >95%) umwandeln3 ... 

Die aus primaren Alkanthiolen sowie aus 2-Mercapto-propan und N-Chlor-succinimid erhaltlichen2 N-Alkylthio-phthalimide reagieren mit Tris-[dimethylamino]-phosphan in Benzol exotherm zu N-Alkyl-phthalimiden, die in ublicher Weise mittels Hydrazin zu den Alkylaminen gespalten werden konnen3. Die Gesamtreaktion stellt also eine Variante der Gabriel-Synthcse dar ... 

Analog reagiert Brom-ethen mit 3,3-Dimethoxy-propen und Piperidin bei 100° (20 h) in Gegenwart von Palladium-acetat und Tris-[2-methyl-phenyl]-phosphan zu 5,5-Dimethoxy-1 -piperidim-2-penten (57%)2. 

The trimerization of cyclopentadiene (6) is catalyzed by a homogeneous bifunctional palladium-acid catalyst system.7 The reaction gives trimers 7 and 8 as a 1 1 mixture in 70% yield with bis(acetylacetonato)palladium(II) [Pd(acac)2] or with bis(benzylideneacetone)-palladium(O) as the palladium component of the catalyst. As the phosphorus component, phosphanes like trimethyl-, triethyl-, or triphenylphosphane, and triisopropylphosphite or tris(2-methylphcnyl)phosphite, are suitable. A third component, an organic acid with 3 < pK < 5, is necessary in at least equimolar amounts, in the reaction with cyclopentadiene (6), as catalytic amounts are insufficient. Acids that can be used are acetic acid, chloroacetic acid, benzoic acid, and 2,2-dimethylpropanoic acid. Stronger acids, e.g. trichloroacetic acid, result in the formation of poly(cyclopentadiene). The new catalyst system is able to almost completely suppress the competing Diels-Alder reaction, thus preventing the formation of dimeric cyclopentadiene, even at reaction temperatures between 100 and 130°C. 

It is important to use dry air and dry equipment because difluorotris(perfluoroalkyl)-25-phos-phanes react very rapidly with water to form tris(perfluoroalkyl)phosphane oxides. Under these conditions, the electrochemical perfiuorination of triethyl-, tripropyl-, and tributylphosphanc oxides yields 15-50% of the corresponding difluorotris(perfluoroalkyl)-A5-phosphanes. A decrease in yield is observed with a longer carbon chain (chain with 2C atoms 42%, with 6C atoms 24 %).63 Byproducts are perfluorinated alkanes. Addition of bromine makes it possible to electrochemically fluorinate trialkylphosphane oxides with a carbon chain length of C5 to... 

Similarly, the reaction between sulfur tetrafluoride and tris(dimethylamino)phosphane proceeds with oxidation of the phosphane in addition to fluorine transfer to give tris(dimethylamino)-difluoro-A5-phosphane (18) as the main product. In contrast, the reaction with tris(methyl-sulfanyl)phosphane does not give a straightforward fluorination extensive Arbuzov-type rearrangements and fluorination reactions occur.220... 

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