Phosphanes, primary

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... 

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... 

A recent development that has gained attention is the characterization of a remarkable series of complexes resulting from the multiple metallation of primary phosphanes, and also a smaller number of the heavier group 15... 

Reviews covering the chemistry of group 2 metal complexes with phosphorus-stabilized carbanions,279 and of molecular clusters of magnesium dimetallated primary phosphanes, are available.2 u Magnesium phosphanes remain rare compounds.281 Lithiation of bromide 98 with BuLi in the presence of tmeda in pentane produces a lithium phosphine dimer subsequent treatment with MgCl2 in EtzO gives the phosphane 99 in 69% overall yield (Equation (19)). The centrosymmetric 99 has Mg-C = 2.217 A Mg-P = 2.77 A (av.).282... 

Molecular Clusters of Dimetalated Primary Phosphanes and Arsanes Matthias Driess... 

MOLECULAR CLUSTERS OF DIMETALATED PRIMARY PHOSPHANES AND ARSANES... 

Dilithiated primary phosphanes could only be isolated in a reproducible crystalline form if the lithiation of the phosphane with BuLi (ratio of 1 2) in toluene was carried out in the presence of a trace amount of LiOH (3). This is evident by the respective transformation of the silylphosphanes 1, which furnished, depending on the steric demand of the silyl group, a dodecameric or a octameric associate (Scheme 1). Thus, reaction of la with BuLi in the molar ratio of 1 2 led to the globular, Li20-filled cluster 5a, whereas metalation of the bulkier substituted phosphane lb gave the Li20-filled octamer 5b. 

Reaction of the primary phosphane Bu3SiPH2 If with MgBu2 furnishes the solvent-free hexameric cluster 17 (Eq. 10) (47). Yellow crystals, have been isolated in 39% yield, which are thermochromic. The NMR spectrum, especially the 31P NMR signal at S = -263.8, suggested that the molecule prefers a high symmetry or dissociates rapidly on the NMR time scale. Since 15 is highly soluble in aromatic hydrocarbons even at low temperature and free of metal oxide, it can thus be regarded as a valuable source of phosphandiide, that is, for nucleophilic RP2 transfer reactions. 

A facile method to form M-P and M-As bonds (M = Al, Ga, In) is represented by the reaction of primary phosphanes and arsanes with E-H containing organometal reagents, which takes place with elimination of H2. Thus, stepwise reaction of iBu2A1H with the primary... 

Whereas the reactions of allenephosphonates 171 (R2 = OEt) with primary aliphatic and aromatic amines 172 and the reactions of the phosphane oxides 171 (R2 = Ph) with aliphatic amines 172 afford the conjugated addition products 173 always in good yields, the addition of anilines to 171 (R2 = Ph) leads to an equilibrium of the products 173 and 174 [231]. However, treatment of both phosphane oxides and phos-phonates of type 171 with hydroxylamines 172 (R3 = OR4) yields only the oximes 174 [232, 233]. The analogous reaction of the allenes 171 with diphenylphosphinoylhy-drazine furnishes hydrazones of type 174 [R3 = NHP(0)Ph2] [234],... 

Based on nucleophilic addition, racemic allenyl sulfones were partially resolved by reaction with a deficiency of optically active primary or secondary amines [243]. The reversible nucleophilic addition of tertiary amines or phosphanes to acceptor-substituted allenes can lead to the inversion of the configuration of chiral allenes. For example, an optically active diester 177 with achiral groups R can undergo a racemization (Scheme 7.29). A 4 5 mixture of (M)- and (P)-177 with R = (-)-l-menthyl, obtained through synthesis of the allene from dimenthyl 1,3-acetonedicar-boxylate (cf. Scheme 7.18) [159], furnishes (M)-177 in high diastereomeric purity in 90% yield after repeated crystallization from pentane in the presence of catalytic amounts of triethylamine [158], Another example of a highly elegant epimerization of an optically active allene based on reversible nucleophilic addition was published by Marshall and Liao, who were successful in the transformation 179 — 180 [35], Recently, Lu et al. published a very informative review on the reactions of electron-deficient allenes under phosphane catalysis [244]. 

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