Synthese, Struktur und einige Reaktionen von Tris‐ und Tetrakis(diphenylphosphino)allen

Abstract

Das aus 1‐(Diphenylphosphino)‐1‐propin (1) mit n‐BuLi erhältliche Reagens Ph2P–CC–CH2Li(2) ergibt bei der Behandlung mit Ph2PCl hohe Ausbeuten an Tetrakis(diphenylphosphino)allen (3). Diese Verbindung liefert nach Oxidation mit H2O2 oder Me3SiOOSiMe3 das Tetraoxid 4a, mit Schwefel oder Selen die entsprechenden Tetrachalkogenide 4b,c. Die Allengruppierung wird dabei nicht angegriffen. Durch Umsetzung von 3 mit MeLi kommt es zur Spaltung einer P–C‐Bindung. Das neben Ph2PMe gebildete 1,3,3‐Tris(diphenylphosphino)allenyllithium (5) kann durch Hydrolyse in (Ph2P)2CCCHPPh2 (6) verwandelt werden. Bei schonender Quartärisierung mit MeI entstehen aus 3 und 6 die Monoquartärsalze 7 und 8, mit überschüssigem Reagens bei erhöhter Temperatur dagegen als gemeinsames Produkt das Phosphonioalkinyl‐semiylid‐Salz [(MePh2P)2C–CC–PPh2‐Me]2+ 2 I− (9). Nebenprodukt der auch hierbei in 3 eintretenden P–C‐Spaltung ist Ph2PMe2+ I−3. – Die Strukturen der Allene 3 und 6 sowie des Salzes 9 wurden durch Röntgenbeugungsanalysen an Einkristallen gesichert. Die Ph2P‐Gruppen in 3 besitzen ähnliche Konformationen wie im analogen (Ph2P)2CCH2 mit jeweils entgegengesetzten Orientierungen der freien Elektronenpaare an den P‐Atomen zur Allen‐Achse. In 6 ist ein Rotameres mit annähernd symmetrischer (“anti”) Orientierung der geminalen Ph2P‐Gruppen vorhanden. 9 ist ein weiteres Beispiel für Semiylid‐Quartärsalze mit delokalisierter Ylid‐Funktion.

Propyne Iminium Salts and Phosphorus(III) Nucleophiles: Synthesis of (3‐Morpholinoallenyl)phosphanes and ‐phosphane Oxides or 1‐(Morpholinopropargyl)phosphanes and ‐phosphonates

“…Both reaction modes give interesting products: C‐1 attack allows the preparation of novel α‐alkynyl‐α‐aminophosphonates, which may be of interest as bioisosters of non‐natural α‐amino acid esters, while the conjugate addition affords 3‐aminoallenylphosphanes and ‐phosphane oxides, which constitute novel 1,3‐bis(donor)‐ and push‐pull‐substituted allenes, respectively. This method for the preparation of phosphorus‐substituted allenes is conceptually different from previous ones, which furnished allenylphosphanes from allenyl anions and phosphorus electrophiles,18,22 and PO‐substituted allenes from propargyl alcohols and chlorophosphanes followed by [2,3] rearrangement 23. We have presented some examples of further transformations of the (3‐morpholinoallenyl)phosphane 4 , which illustrate that selective functionalization of either the enamine or the (vinyl)phosphane functionality is possible.…”

“…Oxidation of the λ 3 ‐phosphorus of 4 to give the corresponding λ 5 ‐phosphorus compounds was also possible 18. Treatment with bis(trimethylsilyl)peroxide gave the allenylphosphane oxide 11 .…”

Unsaturated germanium and phosphorus compounds: reactions of germaphosphenes with .alpha.-ethylene aldehydes and ketones

“…Phosphorus inversion is proved unambiguously by two facts: (1) mesityl groups bonded to germanium in 3a and 3a' are inequivalent (one Mes cis to the aryl group on phosphorus, the other one cis to the phosphorus lone pair) H arom Mes 361 29.79 18.24 18.2 (av) 13.2 (av) at low temperature but become equivalent when the temperature increases and (2) in 5a', there are at -40 °C two diastereoisomers (both C and P are chiral) which change to only one diastereoisomer at room temperature. These phenomena cannot be due to a cyclohexene type inversion: in a change of conformation (from one sofa form to another) mesityls cannot become equivalent and there would be still two diastereoisomers in the case of 5a', as the phosphorus atom remains chiral in this ring inversion; however, such cyclohexene type inversion probably occurs in these derivatives since its magnitude is usually small.…”

Alkali-Metal-Mediated Coupling of a Phosphorus-Substituted Alkene. Structural Characterization of Dilithium 1,1,4,4-Tetrakis(diphenylphosphino)butane-1,4-diide

“…There are few examples of polyphosphines in which there is a similar arrangement of donor atoms: the tetraphosphine (Ph 2 P) 2 CHCH(PPh 2 ) 2 has been isolated as a low-yield product (10−15%) from the oxidation of Li[HC(PPh 2 ) 2 ] by iodine, while the complex {(CO) 4 Mo} 2 { μ -(Ph 2 P) 2 CCHCHC(PPh 2 ) 2 } has been isolated in 16% yield from the photoinduced coupling of an η 2 -bound bis(diphenylphosphino)acetylene ligand, and the same ligand has been isolated as a byproduct of the synthesis of tris(diphenylphosphino)ethene . An example of a tetraphosphinoallene has also been reported …”

“…1 H NMR (500 MHz, [D8]THF, 25 °C): δ 1.75 (m, 16H, THF), 1.91 (m, 4H, CH2), 3.58 (m, 16H, THF), 6.80-7.14 (m, 40H, Ph). 13 distance is 3.147 Å. The binding mode at each end of the diide ligand is typical of diphosphinomethanide complexes, such as the lithium bis(phosphino)methanide {(Ph 2 P) 2 CH}Li(tmeda).…”