Phosphane reactions

Only a few reactions of benzodithiadiazines have been investigated. In common with dithiatriazines 12.8, the anti-aromatic system 12.12 (R = H) undergoes a reversible 5,5 -cycloaddition with norbornadiene. The reaction of 12.12 (R = F) with triphenylphosphine results in a ring contraction to give the imino 2 -phosphane 12.13. ... 

Two intramolecular aza-Wittig reactions leading to 1,3-benzoxazepines have been described. In the first,19 ethyl (Z)-3-(2-acyloxyphenyl)-2-azidoprop-2-enoates 1 are treated with triphenyl-phosphane under argon at 20°C for 3-4 hours when 2-substituted ethyl 1,3-benzoxazepine-4-carboxylates 2 are obtained in 85-90% yield. 

The 3-[2-(acylamino)phenyl]-2-azidoprop-2-enoates 1 undergo a Staudinger reaction on treatment with triphenylphosphane at 20 C to give the stable imino-/.5-phosphanes 2 in nearly quantitative yields. The latter cyclize to 3/7-1,3-benzodiazepines 3 (40-50%) when heated in refluxing xylene for 15 hours. No further details were reported.19... 

Similarly, reaction of the bis(imino-/.5-phosphane) 4 with aroyl chlorides gives 1,3-benzodiazepines, which, however, were assigned the 1//-structures 5. < 3a-b... 

The tricyclic 1,3-diazepines 3 are formed by the action of two molar equivalents of aromatic isocyanates on the bis(imino-A5-phosphane) 1 in toluene at 20 C for 16 hours in a tandem aza-Wittig [2 t 2]-cycloaddition reaction . No further details were reported.167... 

Another route to enantiomcrically pure iron-acyl complexes depends on a resolution of diastereomeric substituted iron-alkyl complexes16,17. Reaction of enantiomerically pure chloromethyl menthyl ether (6) with the anion of 5 provides the menthyloxymethyl complex 7. Photolysis of 7 in the presence of triphenylphosphane induces migratory insertion of carbon monoxide to provide a racemic mixture of the diastereomeric phosphane-substituted menthyloxymethyl complexes (-)-(/ )-8 and ( + )-( )-8 which are resolved by fractional crystallization. Treatment of either diastereomer (—)-(/J)-8 or ( I )-(.V)-8 with gaseous hydrogen chloride (see also Houben-Weyl, Vol 13/9a, p437) affords the enantiomeric chloromethyl complexes (-)-(R)-9 or (+ )-(S)-9 without epimerization of the iron center. 

Incorporation of a chiral phosphane allowed resolution of the complex 6 which was obtained in enantiomerically pure form. Reaction of 6 with 2,2-dimethylpropanal provided the adduct 7 as the sole observable aldol product13. Oxidation of the metal center of 7 with ferric chloride induced decomplexation via reductive elimination, to provide the enantiomerically pure cy-clobutanone 8. 

With diphosphanes recently Stephan et al. reported an intriguing Al and P based macrocyclic structure [37]. A zirconium based catalyst precursor first was employed in the catalytic dehydrocoupling of the primary bidentate phosphane to give the tetraphosphane 6, (Scheme 4). The function of 6 as a molecular building block has been demonstrated by its reaction with MMe3(M = Al, Ga). Although, the gallium derivative 7 has not been... 

Compound 13a can been obtained via two different routes firstly in the reaction of 11 with dimethyl aluminum chloride where LiCl is eliminated and secondly by the reaction of di(pyridyl) phosphane 12 (Py2PH) with trimethyl aluminum where methane is formed, (Scheme 5). The X-ray structure determination of [Me2AlPy2P] 13a, (Fig. 3) elucidates the aluminum atom to be coordinated by the two nitrogen atoms of the pyridyl rings in addition to the two remaining methyl groups leaving the aluminum four... 

Many types of phosphorus-phosphorus bonds are known, but it is rare to find such bonds in hexacoordinated phosphorus compounds (with the exception of 57). Cavell reported in 1998 the reaction of PCI5 with phenylbis(o-(trimethyl-siloxy)phenyl)phosphane, yielding the corresponding bischelate 61 in decent yield (52%) [99]. The octahedral nature of the central phosphorus atom was unambiguously determined by X-ray structural analysis. Two short axial bonds (2.202 A) lie perpendicular to the pseudo-octahedral equatorial plane. 

In a similar way to the aminolysis of the P-N bond mentioned above (Scheme 9), alcoholysis of phosphinous amides leads to the alkyl esters of the respective phosphinous acids [30, 121]. This reaction occurs with inversion of the absolute configuration of the phosphorus atom, and has been used in a synthetic sequence leading to optically active tertiary phosphanes 22 [122] (Scheme 23). 

One of the limitations of the use of asymmetric catalysis comes from the difficulties of separating the chiral catalyst from the reaction medium and recycling it. Such systems are generally formed with chiral phosphane and/or... 

As in CljSn—P(CMe3)3 the metal-coordinated 39 may be interpreted as an ylide-type compound. Reactions and physicochemical measurements indicate that the phosphane acts as a simple donor130>. 

The transmetalation of trimethylsilylphosphanes with germanium and tin halides is a useful way to prepare compounds with P—Ge and P—Sn bonds by simple chlorosilane elimination. The reverse reaction, i. e. formation of P—Si bonds by chlorosilane cleavage of germyl- and stannylphosphanes has not yet been reported. Recently, we observed that hexachlorodisilane "transsilylates di-r-butyl(trimethyl-silyl)phosphane 1 much faster than tetrachlorosilane to give trichlorosilylphosphane 2 ... 

The parent compound, 69, has been synthesized and characterised <2003ZFA1475>. 4-Chloro-hepta-l,6-diene was reacted with Mg. No Grignard rearrangement was noticed but instead the Grignard reagent was converted into l-allyl-3-butenylphosphonous dichloride by reaction with PC13. Reduction with LiAlH. produced l-allyl-3-butenyl-phosphane. Radical-initiated cyclization led to the product, l-phosphabicyclo[3.3.0]octane. Four derivatives were similarly prepared and characterized (70-73). Compound 74 was similarly prepared via a radical reaction < 1997PS(123)141 >. 

Bekiaris et al. have studied the reaction of fluorinated pentane-2,4-diones and phosphanes and have reported the formation of bicyclic compounds and phosphaadamantanes <1997CB1547>. Compounds 167 and 168 were formed in a diasteroselective manner (Scheme 13) and their structures were determined by single crystal X-ray structure analysis. 

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