Insertion reactions with phosphorus compounds

The phosphido complex, U(PPP)4 [165825-64-9] (PPP = P(CH2CH2P(CH3)2), was prepared and fully characterized (216). This complex was one of the first actinide complexes containing exclusively metal-phosphorus bonds. The x-ray structural analysis indicated a distorted bicapped triganol prism with 3—3-electron donor phosphides and 1—1-electron phosphide, suggesting a formally 24-electron complex. Similar to the amido system, this phosphido compound is also reactive toward insertion reactions, especially with CO (216). 

Compound 290 was reacted with dichloro(phenyl)phosphine in the presence of Et3N this led to a ring-opening reaction with the breakage of the 0-CH2 bond, insertion of the phosphorus atom, and formation of the intermediate 291, which gave upon hydrolysis the cyclic phosphoryl-containing product 292 <1998IC4945>. 

In contrast to trivalent phosphorus compounds with activated bonds, where insertion occurs, phosphanes bearing only alkyl, aryl, alkoxy, aryloxy, secondary amino, thio, and halogeno ligands are oxidized by HFA. Earlier work was reviewed by Ramirez (276) in 1970 and Hellwinkel 139) in 1972. The following scheme [Eq. (43)] shows all reactions occurring in the phosphane/HFA system. 

The tetrakis(dialkylphosphido) complexes, An(PPP)4 (An = Th, U) PPP = P(CH2CH2P(CH3)2), were prepared by reacting AnC with four equivalents of the lithium or potassium salt of the PPP tetra-anion. The stmcture of these compounds shows triangulated dodecahedra distorted toward bicapped trigonal prisms. These complexes represent one of the first actinide systems containing exclusively metal-phosphorus bonds. These complexes are known to undergo insertion reactions as seen in actinide amido compounds. ... 

A clean insertion reaction of the 2,3-dihydrophosphole 4 into the zirconium-carbon bond of the transient benzyne-zirconocene 1 occurs when 4 is heated with Cp2ZrPh2 at 80°C for 6 h, leading to the tricyclic compound 5 (Scheme 1). The regioselective formation of 5 can be regarded as the result of a strong interaction between the phosphorus lone pair and zirconium. It can be noted that under the same experimental conditions, the corresponding oxide 4 or the 3,4-di-hydrophosphole 4 do not react with 1. 

Thiazoles can also be derived from 1,4-dicarbonyl compounds, which are available through N-H insertion reactions of rhodium carbenoids <04T3967>. For example, the dirhodium(II) carboxylate-catalyzed reaction of diazocarbonyl compound 7 in the presence of primary amide 8 results in the formation of a-acylaminoketone 9, which is converted into thiazole 10 by treatment with Lawesson s reagent. The cyclodehydration of P-keto thioamide 11 to thiazole 12 is carried out with pyridine-buffered phosphorus oxychloride <04JA12897>. 

Several types of anhydrides of tervalent phosphorus acids are known and have been prepared by electrophilic substitution reactions at phosphorus. Examples are the phosphi-nous acid anhydrides 52 (equation 157), 53 (equation 158), prepared from a chlorophos-phine or an aminophosphine , and 54 (equation 159) Aminophosphines react with carbon disulphide to give ionic addition compounds at low temperatures, but dithiocar-bamate anhydrides (55) at room temperature (equation 160) Aminophosphines form analogous carbamate anhydrides with carbon dioxide, but isothiocyanates give ionic addition products, not insertion products ... 

The C-H insertion reaction of phosphanylidene carbenoid is also found as a typical carbenoid reaction. The copper-mediated oxidative coupling reactions are powerful synthetic tools to construct some conjugated systems with the P=C skeleton, which are operated by treatment of oxygen. Lithium phosphanylidene carbenoids are applicable to synthesize the heavier heteroallenic compounds and stable biradical compounds. Moreover, an intriguing trimerization of phosphanylidene carbenoids is used to give the triphosphafulvene as an isomer of triphosphabenzene, which will lead to a novel organic chemistry. Indeed, the mentioned low-coordinated phosphorus compounds may well be applied to the synthesis of novel materials [5,64,65]. 

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