Phosphoranylidene Phosphoranes

Nitrogen analogues (6.457) were first prepared as long ago as 1919 by the Staudinger reaction (7.416). They also undergo Wittig-type (Aza-Wittig) reactions. 

Most phosphoranylidene phosphoranes known at present, appear to be unstable and decompose in solution. 

---

Imino-ethenyliden)-phosphorane wie l-Pheny]imino-2-(triphenyl-phosphoranyliden)-ethen I lagern sich an NH-Bindungen an und bilden Phosphorane II, die mit Aldehyden weiter zu einer Vielzahl von Alkenen III kondensieren. Mit Benzimidazol erhalt man z. B.527 ... 

Although strictly outside the remit of this chapter, it is appropriate to note continued activity in the chemistry of c X -p -bonded phosphorus compounds that do not possess a lone pair of electrons at phosphorus. A monomeric metaphosphonate species (262, X=0) has been stabilised by coordination via the P=0 bond), and Harger s group has provided evidence of the intermediacy of metathiophosphonates (262, X=S) in the reactions of phosphonami-dothioic acids with alcohols.The cation (263) has been stabilised by coordination at phosphorus with 4-dimethylaminopyridine and the reactivity of bis(methylene)phosphoranes (264) and related phosphoranylidene car-benoids has been investigated. ... 

Phosphoranylidene carbenoid 7A was also obtained by proton abstraction of the phosphorane 12 [22] (Scheme 7). 

All reactions were carried out at 180 °C and using PI1CH2CN, DMC in a 1 18 molar ratio. Bases were used in 0.05 mol cquiv. with respect to PhCH2CN. hEntries 5-6 rm-butyliminoUis(dimethylamino)phosphorane and l-tert-butyl-4,4,4-iminotris (dimethylamino)- 2 -bis [tris (dimethylamino) phosphoranylidene amino]-2X,, 4A, -catenadi(phosphazene) were used as bases (Fluka Art. N. 79408 and 79421, respectively) both were completely soluble in DMC. Solubility of alkaline carbonates in DMC was determined by titration (20). Conversions determined by GC. Selectivity is defined as [(mol of PhCH(CH3)CN)/(mol of PhCH(CH3)CN + PhC(CH3)2CN)l X 100. 

---