ChemInform Abstract: N‐(α‐Dialkoxyphosphorylalkyl)imidoylphosphonates.

Onys’ko, P. P.; Kim, T. V.; Kiseleva, E. I.; Sinitsa, A. D.

doi:10.1002/chin.199051255

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“…Hence, in the presence of Et 3 N, compounds Ia and Ib (R = H) isomerize completely at room temperature within 3 h, while the degree of isomerization of imidoylphosphonate Ic (R = Me) is only 45%, and the process completes within 15 h. The proton at the N-methine carbon atom in imidoylphosphonates is less mobile than in the N-methyl or N-methylene analogs. As we showed previously [4,5], N-a-phenylethyltrifluoroacetylimidoylphosphonates Ii and Ij undergo isomerization when heated in the presence of bases (Et 3 N, diazabicyclooctane, diazabicycloundecene). The proton transfer is irreversible and stereoselective, which allows preparation of enantiomerically enriched phosphorus analogs of trifluoroalanine [1,5].…”

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confidence: 59%

“…As we showed previously [4,5], N-a-phenylethyltrifluoroacetylimidoylphosphonates Ii and Ij undergo isomerization when heated in the presence of bases (Et 3 N, diazabicyclooctane, diazabicycloundecene). The proton transfer is irreversible and stereoselective, which allows preparation of enantiomerically enriched phosphorus analogs of trifluoroalanine [1,5]. Analogous results with these compounds were later obtained by Xiao et al [9].…”

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confidence: 59%

“…, Ph (f) [4]; Alk = i-Pr, R`= H, R = CF 3 (g); Alk = Me, R = H, R`= Ph (h) [4]; R = Me, R`= Ph, Alk = Et (i) [4,5], i-Pr (j) [1]; Alk = Et, R + R`= (CH 2 ) 4 (k). II, III, R = H, R`= H (a) [1], Me (b), CH 2 OMe (c), CF 3 (d), Ph (e) [4]; R + R`= (CH 2 ) 4 (f); R = Me, R`= Ph (g) [4,5].…”

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confidence: 99%

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Sigmatropic Isomerizations in Azaallyl Systems: XXII. 1,3-Proton Transfer in (N-Alkyltrifluoroacetimidoyl)phosphonates

et al. 2005

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The reaction of N-alkyltrifluoroacetimidoyl chlorides with trialkyl phosphites leads to corresponding imidoylphosphonates CF 3 C[P(O)(OAlk) 2 ]=NCH 2 R. These compounds undergo irreversible 1,3-H shift catalyzed by nitrogenous bases to give phosphorylated imines CF 3 CH[P(O)(OAlk) 2 ]N=CHR. The tendency for prototropism increases with increasing electronegativity of substituents R: CF 3 > CH 2 OMe > H > Me. N-Cyclopentyl analogs of the obtained compounds show no tendency for prototropism. Imidoylphosphonates exist mainly as Z isomers [Z/E~(6310) : 1].Imidoylphosphonates are promising synthetic precursors of biologically important derivatives of a-aminophosphonic acids. As they are the [oxidized] form of a-aminophosphonates, reduction of the C=N bond (conversion PC=N 6 PCHN) is a way of their transformation into a-aminophosphoryl derivarives.Intramolecular proton transfer that simulates biochemical transamination allows this process to be performed in the absence of a foreign reducing agent. In previous communications of this series we showed that 1,3-H transfer is characteristic of benz-[2] and some alkanimidoylphosphonates [1]. In the present ÄÄÄÄÄÄÄÄÄÄÄÄ work we synthesized (N-alkyltrifluoroacetimidoyl)-phosphonates I and considered the effect of substituents in the N-alkyl radical on the 1,3-H transfer. The electron-acceptor and simultaneously fairly chemically inert trifluoromethyl group on the sp 2 -carbon atom of compound I favors proton transfer and thus allows synthesis of phosphorus analogs of trifluoroalanine that act as enzyme inhibitors [1,3].Imidoylphosphonates I were prepared by reaction of trialkyl phosphites with imidoyl chlorides II obtained by chlorination of trifluoroacetamides III (Scheme 1). Scheme 1. ; = o ; = g O R CF 3 N R`7 76 X 2 PCl 3 ; o ; = g O R CF 3 R`7 76 I N (AlkO) 3 P ; CF 3 I g

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Sigmatropic Isomerizations in Azaallyl Systems: XXII. 1,3-Proton Transfer in (N-Alkyltrifluoroacetimidoyl)phosphonates
Onys’ko
¹
,
Kim
²
,
Kiseleva
³

et al. 2005
Russ J Gen Chem
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The reaction of N-alkyltrifluoroacetimidoyl chlorides with trialkyl phosphites leads to corresponding imidoylphosphonates CF 3 C[P(O)(OAlk) 2 ]=NCH 2 R. These compounds undergo irreversible 1,3-H shift catalyzed by nitrogenous bases to give phosphorylated imines CF 3 CH[P(O)(OAlk) 2 ]N=CHR. The tendency for prototropism increases with increasing electronegativity of substituents R: CF 3 > CH 2 OMe > H > Me. N-Cyclopentyl analogs of the obtained compounds show no tendency for prototropism. Imidoylphosphonates exist mainly as Z isomers [Z/E~(6310) : 1].Imidoylphosphonates are promising synthetic precursors of biologically important derivatives of a-aminophosphonic acids. As they are the [oxidized] form of a-aminophosphonates, reduction of the C=N bond (conversion PC=N 6 PCHN) is a way of their transformation into a-aminophosphoryl derivarives.Intramolecular proton transfer that simulates biochemical transamination allows this process to be performed in the absence of a foreign reducing agent. In previous communications of this series we showed that 1,3-H transfer is characteristic of benz-[2] and some alkanimidoylphosphonates [1]. In the present ÄÄÄÄÄÄÄÄÄÄÄÄ work we synthesized (N-alkyltrifluoroacetimidoyl)-phosphonates I and considered the effect of substituents in the N-alkyl radical on the 1,3-H transfer. The electron-acceptor and simultaneously fairly chemically inert trifluoromethyl group on the sp 2 -carbon atom of compound I favors proton transfer and thus allows synthesis of phosphorus analogs of trifluoroalanine that act as enzyme inhibitors [1,3].Imidoylphosphonates I were prepared by reaction of trialkyl phosphites with imidoyl chlorides II obtained by chlorination of trifluoroacetamides III (Scheme 1). Scheme 1. ; = o ; = g O R CF 3 N R`7 76 X 2 PCl 3 ; o ; = g O R CF 3 R`7 76 I N (AlkO) 3 P ; CF 3 I g
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“…Mixing of equimolar amounts of imidoylphosphine oxide VI (d P 20.1 ppm) and boron trifluoride etherate in benzene gives complex VIII (d P 33.5 ppm) (cf. [10]) with a more electrophilic phosphonium center favoring 1,3-H transfer in the C=N3C triad [4,5,7,8]. However, here, too, no prototropic shift takes place.…”

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confidence: 92%

“…By contrast, N-benzimidoyl chlorides III (R = H, R`= Ar) under the same conditions react with phosphite IVa to give a mixture of prototropic isomers I and II [5], whereas the reaction with phosphinite IVb results in preferential formation of isomer II [7]. The more complete isomerization in the last case is explained by the fact that 1,3-H shift takes place mainly in intermediate C, because the strongly electron-acceptor phosphonium group favors proton transfer [4,5,7,8].…”

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Sigmatropic isomerizations in azaallyl systems: XX. N-Alkylbenzimidoylphosphonates
Onys’ko
¹
,
Kim
²
,
Rassukana
³

et al. 2004
Russ J Gen Chem
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Synthetic approaches are developed to benzimidoylphosphoryl derivatives containing electronically and sterically diverse alkyl substituents on the nitrogen atom, as well as their prototropic isomers. Regularities in prototropic transitions in the phosphorylated C=N!C triad were revealed and applied in the synthesis of =-aminophosphonic acid derivatives.Imidoylphosphonates containing a-hydrogen atoms in the N-alkyl group are potential 1,3-prototropic systems. Prototropy the phosphorylated C=N3C 1,3-prototropic triad presents both theoretical and practical interest. The A 76 47 B interconversion can be regarded as a [phosphorus] model of the biochemical transamination reaction in living bodies.The 1,3-prototropic shift in the phosphorylated azaallyl triad makes evident genetic relation between derivatives of imidoylphosphonic (A) and a-aminoalkylphosphonic acids (B) that attract increased interest in view of their biological activity [2, 3].Transformations like A 6 B belong to fundamental properties of imidoylphosphonates and form an important method for preparing a-aminoalkylphosphoryl derivatives [4].In previous communications of this series we showed that the phosphorus-containing group controls facility and direction of prototropic migrations in the C=N3C triad. In detail it was established [4,5] that N-benzylbenzimidoylphosphoryl derivatives I under mild conditions, even in the absence of bases, undergo an irreversible 1,3-prototropic shift to form Nbenzylidene-a-aminoalkylphosphoryl derivatives II (Scheme 1).To assess the effect of the N-alkyl substituent on the prototropy in the C3N3C triad, in the present work ÄÄÄÄÄÄÄÄÄÄÄÄ 1 For communication XIX, see [1]. Scheme 1.; C 9 0 P ; 9 0 P = T

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Sigmatropic isomerizations in azaallyl systems: XXI. Alkanimidoylphosphonates and their prototropic and phosphorotropic isomers
Onys’ko
¹
,
Kim
²
,
Kiseleva
³

et al. 2004
Russ J Gen Chem
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Synthetic procedures for alkanimidoylphosphoryl derivatives with a-hydrogen atoms in the N-alkyl radical are developed. Data on the effect of substituents at the carbon and phosphorus atoms on the facility of prototropic transitions in the C=N3C triad are summarized. The most facile proton transfer occurs in the N-benzyl derivatives, and the prototropic isomer is the more stable, the stronger the electron-acceptor power of the substituent at the sp 3 -carbon atom of the azaallyl triad. The proton transfer in N-(a-phenethyl)-trifluoroacetimidoylphosphonates proceeds selectively, which allows preparation of enantiomerically enriched derivatives of a-aminotrifluoroethylphosphonic acid. A specific effect of substituents at the phosphorus atom on the prototropism attendant on phosphorylation of imidoyl chlorides is demonstrated.The methylene3azomethine system is one of the least labile prototropic triads. An electron-acceptor phosphorus-containing group at the sp 2 -carbon atom of the C=N3CH triad much increases the lability of the proton and thus renders such compounds labile prototropic systems [2]. Proton transfer in phosphorylated azaallyl derivatives is synthetically attractive, providing a way to converting imidoylphosphonic to biologically important a-aminophosphoryl compounds [3,4]. The 1,3-phosphorotropic isomerization we discovered in the C=N3CH triad [5, 6] permits to perform interconversions of different a-aminophosphoryl derivatives.In the present work we considered the effect of alkyl groups at the sp 2 -and sp 3 -carbon atoms of a phosphorylated azaallyl triad on the facility of 1,3-prototropic and phosphorotropic transitions, as well ÄÄÄÄÄÄÄÄÄÄÄÄ as the effect of substituents on the phosphorus atom on the prototropism attendant on phosphorylation of imidoyl chlorides.As one of the synthetic approaches to imidoylphosphoryl compounds, we for the first time used the azaWittig reaction with acetylphosphonate I as the carbonyl component. It was found that imidoylphosphonate III formed by the reaction of oxophosphonate I with phosphazo compound II undergoes irreversible isomerization to a-phosphorylated benzalimine IV under the reaction conditions. The preference for the imine3imine isomerization over the imine3enamine rearrangement III 6 V (Scheme 1) is assignable to the possibility of effective conjugation of the C=N bond with the phenyl ring in N-benzylidene structure IV, which makes this structure favorable [2,7].

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ChemInform Abstract: N‐(α‐Dialkoxyphosphorylalkyl)imidoylphosphonates.

Abstract: ChemInform Abstract The title compounds (III) are prepared by condensation reaction of the acylphosphonates (I) with the α-aminoalkylphosphonates (II) in the presence of p-toluenesulfonic acid.

Cited by 8 publications

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Sigmatropic Isomerizations in Azaallyl Systems: XXII. 1,3-Proton Transfer in (N-Alkyltrifluoroacetimidoyl)phosphonates

Sigmatropic Isomerizations in Azaallyl Systems: XXII. 1,3-Proton Transfer in (N-Alkyltrifluoroacetimidoyl)phosphonates

Sigmatropic isomerizations in azaallyl systems: XX. N-Alkylbenzimidoylphosphonates

Sigmatropic isomerizations in azaallyl systems: XXI. Alkanimidoylphosphonates and their prototropic and phosphorotropic isomers

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