Nitrilium phosphanylid complexes

Streubel R (2003) Transient Nitrilium Phosphanylid Complexes New Versatile Building Blocks in Phosphorus Chemistry. 223 91-109 Stutz AE, see Hausler H (2001) 215 77-114 Sugihara Y, see Nakayama J (1999) 205 131-195... 

Streubel R (2003) Transient Nitrilium Phosphanylid Complexes New Versatile Building Blocks in Phosphorus Chemistry. 223 91 -109... 

Keywords. Azaphospholes, Azaphosphirenes, 1,3-Dipoles, Heterophospholenes, Nitrilium Phosphanylid Complexes... 

H-Azaphosphirene Complexes, a NdfwraZ Starting Point for Nitrilium Phosphanylid Complexes . 

The aim of the present work is to show preparative and theoretical aspects of the formation of transient nitrilium phosphanylid complexes, a novel 1,3-dipole system, and to highlight their synthetic potential in organophosphorns chemistry with special emphasis on unsaturated five-membered N,P-heterocycles. This review covers the literature until November 2001. 

M = Cr, W R = CH(SiMe3)2 pip = 1-piperidino Scheme 5. Intramolecular valence isomerization of nitrilium phosphanylid complexes [25]... 

Synthesis of N,P-Heterocyclic Ligands with the P-N=C Structural Moiety via Trapping of Transient Nitrilium Phosphanylid Complexes... 

So far, only very few reactions were reported on the use of 2H-azaphosphirene complex 11a in nitrilium phosphanylid complex chemistry, mainly because of the tendency of P-CjMes-substituted derivatives to undergo side reactions [47]. Nevertheless, it seems worthwhile to look at the reaction of 11a with DMAD, which finally led to the 1 -aza-7-phosphanorbornadiene complex 13 via 2H-l,2-azaphosphole complex 12 as reactive intermediate (Scheme 9) [48]. Later on, complex 12 was isolated and characterized using a different stoichiometry [49]. 

A real landmark in the generation of transient nitrilium phosphanylid complexes was the discovery that 7-phosphanorbornadiene complexes could be also employed, e.g., the complexes 14a,b in the synthesis of 2H-l,2-azaphosphole complexes 16a,b (Scheme 10), thus offering now the possibility to study the reactivity of sterically less encumbered 1,3-dipole species such as 15a,b [34]. Note worthy is the absence of any by-products such as A -l,3,2-oxazaphospho-lene complexes (cf. Scheme 7) in these reactions. Even more fascinating are perspectives to use 7-phosphanorbornadiene complexes with P-functional substituents in 2H-l,2-azaphosphole complex chemistry. 

Scheme 14. Synthesis of the first 2H-l,2,3-azadiphosphole complexes using transient nitrilium phosphanylid complexes [55]...

Scheme 15. Intramolecular [3 + 2] cycloaddition reaction of a nitrilium phosphanylid complex...

Very recently, another fascinating example of such a reaction of a transient nitrilium phosphanylid complex was found - the intramolecular addition in 25 to a phenyl group of the Wittig-ylid substituent to furnish complex 26 [56]... 

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