Phosphino amide

In contrast, the phosphino amide derivatives are isolated as air and moisture stable solids. Although they still have an aminic proton, the use of excess acetylacetonate does not produce further deprotonation. Their 31P NMR spectra suggest the presence of a rapid exchange equilibrium in solution, in which the remaining aminic hydrogen changes its position from one nitrogen to the other, even at low temperature [Eq. (21)]. 

Fig. 5.3 Possible structures of a lithium phosphino amide and the expected effect on the phosphorus chemical shift for each...

Not all phosphino amides resonate downfield from their respective phosphino amines. In Fig. 5.4, we see an example for an upfield shift of A< =-12ppm upon deprotonation. The upfield shift is very modest due to intermolecular hydrogen bonding (explained below). In the heterocyclic structure of the amide, the additional electron density due to deprotonation stays on the nitrogen atom. The potassium atom is coordinated by the oxygen and sulfur atoms. 

Fig. 5.5 Comparison of phosphorus chemical shifts between phosphino amines, phosphino amides, and phosphino ureas...

The first examples of phosphirenium salts (129) have been prepared from the reactions of alkynes with the aluminium trichloride adducts of dichlorophos-phines. The reactions of phosphines with fluorotrihalogenomethanes lead to the first examples of fluorine-containing phosphoranium salts (130). The related nitrogen-bridged salt (131) is formed in the reactions of lithium bis(diphenyl-phosphino)amide with iodomethane. ... 

A limited number of phosphino amides and imides of types R2PNH2, (R2P)2NH or RP(NH2)2 can be prepared, for example. 

Reagents obtained by lithiation of ort/io-haloarylphosphines have been used in routes to new substituted arylphosphines, e.g., (69), (70), and (71). C-lithiated phosphinocyclopentadienides, e.g., (72), have been used in routes to dissymmetric heteroannular-functionalised ferrocenylpolyphosphines, e.g., (73). The reagent PhP(CH2CH2SLi)2 has been applied in a route to new phosphathiamacrocycles, e.g., (74). Apart from their applications in synthesis, interest has also continued in the preparation and structural characterisation of various C-metallated complexes of borane-protected alkyl- and silylated alkyl-phosphines, ° C-metallated potassium-and lanthanum-complexes of l,2-bis(diphenylphosphino)methane, and also of alkaline earth and rare earth N-metallated complexes of a variety of phosphino-amides. ... 

Also covered by this review are those compounds bearing two or three phosphane units at the same N atom, that is those derived from (H2P)2NH (N-phosphino phosphinous amide in CAS nomenclature) and from (H2P)3N, NJsl-bis(phosphino) phosphinous amide, but not those bearing more than one amino... 

M,JV-Bis(phosphino) phosphinous amides N(PR2)3, commonly called triphos-phinoamines, are still virtually unknown, with the exceptional reported existence of N(Pp2)3 and N[P(CH3)2]3 [15,19,20]. The usual synthetic approaches to N(PPh2)3 give instead the isomeric Ph2P-P(Ph2)=N-PPh2 [25]. 

These phosphinous amide anions are presumably responsible for the formation of the by-products AT-phosphino phosphinous amides 11 and mono-phosphazenes derived from diphosphanes 12 in the sequential treatment of primary amines with n-BuLi and chlorophosphanes for preparing NH phosphinous amides [75,88] (Scheme 14). Compounds 11 and 12 are presumably derived from anions 9 and 10, respectively, generated by deprotonation of the newly formed phosphinous amide with the lithiated amine R NHLi. In solution, 9 can establish a metallotropic equilibrium with 10. 

A number of NH phosphinous amides have been P-alkylated by previous conversion to their corresponding anions [59,74]. A particular case of double alkylation takes place with the anion derived from the AT-phosphino phosphinous amide NH(PPh2)2 yielding the diphosphonium salt 17 [102] (Scheme 17). When neutral, its methylation is reported to give the P-H phosphazene-phos-phonium salt 18 [103]. 

Occasionally, attempts at introducing a new PR2 group on the nitrogen atom of an NH phosphinous amide, with the aim of preparing Ar,AT-bis(phosphino) phosphinous amides, result in the generation of monophosphazenes derived from diphosphanes, as seen in the preparation of 20 which occurs by P-P bond formation [74] (Scheme 20). The authors of this work claimed that the electron-... 

Following the general trend of this account, monodentate phosphinous amide ligands and bidentate AT-phosphino phosphinous amides or bis(amino-phosphanes) are included in the following discussion, but not other bidentate ligands bearing additional, different phosphorus functionalities, as for instance phosphinous amide-phosphane bidentate ligands. 

The amide [Sm(45a) N(SiMe3)2 ] was a catalyst for an aUene-based hydroamination/ cyclisation. As an illustration, one such product upon hydrogenation yielded a naturally occurring alkaloid. Scheme 4.8. " " The same samarium(lll) amide was also active for the intramolecular hydrophosphination/cyclisation of phosphino-alkenes or -alkynes e.g., H2P(CH2)3C=CPh was transformed into 76. " ... 

The regioseledivity of the last reaction in Scheme 5.13 is not only because of the greater acidity of the methylene group, but also because some secondary and tertiary amides (e.g. /3-arylamides, /3-vinylamides, or /3-(phenylthio)amides, or borane complexes of /3-phosphino propionamides [132, 133]) are deprotonated at the /3 position under kinetic control to yield chelate-stabilized carbanions [58, 134], Illustrative examples of such remarkable metalations are shown in Scheme 5.14. 

Temelkoff DP, Smith CR, Kibler DA, McKee S, Duncan SJ, Zeller M, Hunsen M, Norris P. Application of bis(diphenyl-phosphino)ethane (DPPE) in Staudinger-type A-glycopyranosyl amide synthesis. Carbohydrate Res. 2006 341 1645-1656. 

The e.s.r. spectra of o and n radicals and radical ions that had been reported up to 1974 have been reviewed. The similarity of u(P) of the P amide radical (109) with values for other phosphino radicals indicated that they might have comparable... 

Preparation of Phosphines by Addition of P-H to Unsaturated Compounds. -This route has not received much attention over the past year. A stereoselective synthesis of tris(Z-styryl)phosphine is offered by the addition of phosphine to phenylacetylene in a superbasic system (HMPA-H20-K0H)." In a similar vein, the reaction of phosphine with styrene and a-methylstyrene in a superbasic medium (DMSO-KOH) provides a route to the primary phosphines, (2-phenylethyl)phosphine and (2-methyl-2-phenylethyl)phosphine, respectively. 7 Transition metal phosphine complexes have been shown to catalyse the a-hydroxylation, P-cyanoethylation, and P-alkoxycarbonylethylation of phosphine. 71 Addition of primary phosphines to acrylic esters has been used for the synthesis of the phosphines (80).7 A similar addition of diphenylphosphine to acrylic esters and amides has given a series of hydrophilic phosphines (81). 72 The bis(phosphorinanyl)ethane (82) is formed in the photochemical addition of l,2-bis(phosphino)ethane to 1,4-pentadiene. ... 

As mentioned in Volume 13 of these Reports, 4-oxoazetidin-2-yl phosphonates and phosphinates (19) can be prepared by Arbusov-like reactions between P compounds and 4-acetoxyazetidin-2-one (20). Acid hydrolysis of (19) yields phosphono- and phosphino-aspartic acids (21) which can be converted into peptides with antibacterial activity. Diastereomeric mixtures of phosphono-dipeptides, which can be prepared from racemic dialkyl 1 -aminoalkylphosphonates, can be separated by ion-exchange chromatography. It appears that it is easier to synthesize phosphonodipeptides from these phosphonates as their P-dialkyl esters rather than as the free phosphonic acids. Phosphonic acid analogues of A-Cbz-alanine and -phenylalanine can be converted into ester and amide fluoridates, e.g., (22, R = OMe or NHCHMeg). These fluoridates are the most potent inhibitors of elastase and chymotrypsin yet reported and seem to mimic the natural substrates of these enzymes. ... 

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