Tetrahedral Phosphorus Atom Research Articles

Synthesis of Phosphinopeptides via the Mannich Ligation

Phosphinopeptides are a class of unnatural peptides containing a tetrahedral phosphorus atom and have potential for use as enzyme inhibitors. A series of phosphinopeptides were synthesized via the Mannich-type reaction of aryldichlorophosphines, aldehydes, and N-protected amino amides or peptide amides and subsequent aminolysis with amino esters or peptide esters. The current method named the Mannich ligation is an efficient route to synthesis of phosphinopeptides through convergent condensation.

New Anions of Pentacoordinate Phosphorus Containing Fluorine and Trifluoromethyl Groups

AbstractThe unique pseudo‐trigonal‐bipyramidal CF3PF3O– and (CF3)2PF2O– anions were obtained and characterised for the first time. They were formed by the reactions of (PhO)3P(O), Me3SiCF3 and the fluoride ion sources [Me4N]F and CsF, respectively, in glyme. These anions represent the stable transition states postulated for nucleophilic substitution at a tetrahedral phosphorus atom. The salt Cs[(CF3)2PF2O] (7) is stable at room temperature for a month, while [Me4N][CF3PF3O] (1) dismutates into [Me4N][CF3PF(O)O] (2) and [Me4N][CF3PF5] (3) above 0 °C. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Trans-2-(Dimethoxyphosphinoyl)-1-phenyl-1-(1,1,3,3-tetramethyl-2,3-dihydro-1H-isoindol-2-yloxy)ethene

The structure of the compound CHNOP was investigated. The central feature of the compound is a tetrahedral phosphorus atom attached to two methoxy groups, a phosphate oxygen and an isoindoloxy group. There is a possible C2-H2···N5 intramolecular hydrogen bond and an intermolecular link. The compound is important for the study of the reaction of phosphorus-centered radicals with alkenes and alkynes.

Zum reaktionsverhalten von dialkyl(trichlorsilyl)phosphanen — verglichen mit tri methylsilylphosphanen — gegenüber dichlordimethylstannan: Austauschreaktionen and strukturen cyclischer chlorstannylphosphan-dichlordimethylstannan-addukte

Di-isopropyl(trichlorosilyl)phosphane ( 2a) is less reactive towards Me 3SnCl, tBu 2PSnMe 2Cl ( 5b) and Me 2SnCl 2 than di-isopropyl(trimethylsilyl)phosphane ( 3a). Compound 3a reacts with each of the organotin chlorides to provide iPr 2PSnMe 3 ( 1a), ( iPr 2P) 2SnMe 2 ( 6a) or mixtures of ( tBu 2P) n ( iPr 2P) 2− n SnMe 2 ( n=0, 1, 2: 6a, c, b), but 2a reacts with Me 2SnCl 2, providing only iPr 2P(μ-SnMe 2Cl) 2Cl ( 4a), which has the composition of a 1:1 adduct of iPr 2PSnMe 2Cl ( 5a) with Me 2SnCl 2. Compound 4a is not further attacked by excess of 2a. Similarly, di-t-butyl(trichlorosilyl)phosphane ( 2b) reacts only with two equivalents of Me 2SnCl 2 providing tBu 2P(μ-SnMe 2Cl) 2Cl ( 4b). X-Ray structure determinations of the unusual compounds R 2P[(μ-SnMe 2Cl) 2Cl) ( 4) ( 4a: R = iPr; 4b: R = tBu) reveal that the cyclic ‘adducts” 4 are the first compounds described containing two tin atoms of coordination number five bridged by a four-coordinated (slightly distorted) tetrahedral phosphorus atom. The cyclic structures of 4 involving stannylphosphanes 5a,b as donors and acceptors towards Me 2SnCl 2 are consistent with previous predictions from 119mSn Mössbauer, NMR and IR/Raman data of 4b. The solid-state structures of 4a and 4b allow an insight into the role of pentacoordinated tin in the course of silyl/stannyl-phosphane exchange reactions and the long-known rapid self-exchange reactions of trimethylstannylphosphanes with trimethylstannyl halides.

Inhibitors of angiotensin-converting enzyme containing a tetrahedral arsenic atom

A series of tetrahedral oxo acids of Group VA and VIA elements and of silicon and boron were examined as inhibitors of angiotensin-converting enzyme. Arsenate is a competitive inhibitor with a Ki of 27 +/- 1 mM, at least 10-fold more potent than phosphate. Dimethylarsinate is a competitive inhibitor with a Ki of 70 +/- 9 mM, 2-fold more potent than dimethylphosphinate. Oxo acids of boron, silicon, antimony, sulphur and selenium are not inhibitors. On the basis of these results and the strong inhibition of this zinc metallopeptidase by substrate analogues containing a tetrahedral phosphorus atom, two substrate analogues containing a tetrahedral arsenic atom were prepared. 2-Arsonoacetyl-L-proline is a competitive inhibitor with a Ki of 18 +/- 7 mM, more than 2000-fold weaker than that of its phosphorus analogue 2-phosphonoacetyl-L-proline. 4-Arsono-2-benzylbutanoic acid is a mixed inhibitor with a Ki of 0.5 +/- 0.2 mM, indistinguishable in potency from its phosphorus analogue 2-benzyl-4-phosphonobutanoic acid.

Phosphonodipeptides containing (2-aminoethyl)phosphonic acid (ciliatine): transition state analogue inhibitors of carboxypeptidase A

The phosphonodipeptides having a structure of Cbz-NH(CH 2) 2PO(O −Li +)-NHCHRCO 2 −Li + (Cbz = carbobenzyloxyl; amino acid residues Gly, l-Ala and l-Phe) were found to inhibit competitively the hydrolysis of Cbz-Gly-Gly- lPhe-OH by carboxypeptidase A. The compound having an l-phenylalanine residue was especially effective, giving K i values of about 10 −8 and 10 −9 M at pH 7.5 and 6.0 (25°C), respectively. The kinetics suggested that (i) an ionized P-O − group of the inhibitors with a tetrahedral phosphorus atom forms a coordinating bond with a zinc ion of the enzyme and (ii) the amino acid side-chains of the inhibitors are accommodated in the hydrophoic pocket of the enzyme. The inhibitory activity of the phosphonodipeptides was explained by a transition state analog mechanism.

Reactions of phosphonic acid esters with nucleophiles. Part IV. Hydrazines and hydroxylamines with p-nitrophenyl methylphosphonate

A steric argument accounts for the orders of reactivity of two parallel series of hydrazines and hydroxylamines with p-nitrophenyl methylphosphonates. The α effect is not especially important. The unusually high reactivity of hydroxylamine may reflect O-attack for this species. In some cases hydrogen bonding to the phosphoryl oxygen atom in the transition state is a possibility. The results agree with prevailing theories on the forces which control nucleophilic substitution at a tetrahedral phosphorus atom.

Routes for the formation of 1,2-oxaphospholene derivatives by the reaction of?-keto alcohols with the acid chlorides of trivalent phosphorus acids

1. A number of oxaphospholene derivatives was obtained by the reaction of the acid chlorides of trivalent phosphorus acids withβ-keto alcohols. 2. A five-step scheme for the progress of the reaction was proposed. 3. Considerations were expressed regarding the possibility of compounds, containing chlorine and hydrogen attached to the same tetrahedral phosphorus atom, taking part in the intermediate steps.

Study of conjugation in N-methylphosphamidines-systems with a tetrahedral phosphorus atom

1. The kinetics of the reaction of P,P-diethyl-N-methyl-N,N′-diarylphosphamidines with methyl iodide was studied. 2. The basicities of P,P-diethyl-N-methyl-N,N′-diarylphosphamidines in nitromethane were determined. 3. The rate constants of methylation and the basicities of P,P-diethyl-N-methyl-N,N′-diarylphos-phamidines are linearly correlated with the Hammett σ constants or with the nucleophilic σ- constants; moreover, in the latter case the correlation is better. 4. From a comparison of the rate constants of methylation and the basicity constants of two series of phosphamidines, it was found that the tetrahedral phosphorus atom in the phosphamidines studied transmit the polar influences of the substituents at the nitrogen atoms without any change in the ratio of the inductive and resonance components, weakening this influence by approximately 50–60%.

Investigation of the dual reactivity of phosphamidine anions

1. The kinetics of the reaction of sodium derivatives of O,O-diethyl-N,N′-diarylphosphamidines with methyl iodide was studied. A kinetic analysis was performed and the particular rate constants were calculated. The direction of methylation is determined by the polar influence of the substituents in accord with the Hammett equation. 2. The tetrahedral phosphorus atom in phosphamidine anions transmits the polar influence of substituents at the nitrogen atoms, weakening this influence approximately by half.

Conjugation in systems involving a tetrahedral phosphorus atom

Conjugation in systems involving a tetrahedral phosphorus atom

Trialkyl acylphosphorimidates as conjugated systems

Triethyl acylphosphorimidates are characterized by their ability to undergo substitution reactions of not only the 1,2-type, but also the 1,4-and 1,6-types. It is thus confirmed that a tetrahedral phosphorus atom can be included in the conjugated chain $$O = \mathop C\limits_| - N = \mathop P\limits_|^| - O - \mathop C\limits_|^| - .$$

Conjugation in non-coplanar systems involving a tetrahedral phosphorus atom

Conjugation in non-coplanar systems involving a tetrahedral phosphorus atom