Addition Of Phosphite Research Articles

Behavior of 3,6-bis(vinylsulfonyl)-1,2,4,5-tetrafluorobenzene in homolytic addition of dialkyl phosphites

Reaction of 3,6-bis(vinylsulfonyl)-1,2,4,5-tetrafluorobenzene with dialkyl phosphites at thermal initiation (70°C) gives rise to 3,6-bis(dialkoxyphosphonoethylsulfonyl)-1,2,4,5-tetrafluorobenzenes in up to 45% yield. The formation of diethoxyphosphonyl radicals in the course of the reaction was observed with the use of ESR method applying spin trapping by 2-methyl-2-nitrosopropane. The use as initiator of the azo-bis-isobutyronitrile increased the yield of diadducts to 60%.

Stereoselective synthesis of the 5'-hydroxy-5'-phosphonate derivatives of cytidine and cytosine arabinoside.

Both the (R)- and (S)-5'-hydroxy 5'-phosphonate derivatives of cytidine and cytosine arabinoside (ara-C) have been prepared via phosphite addition or a Lewis acid mediated hydrophosphonylation of appropriately protected 5'-nucleoside aldehydes. Phosphite addition to a cytosine aldehyde protected as the 2',3'-acetonide gave predominately the 5'R isomer, while phosphite addition to the corresponding 2',3'-bis TBS derivative favored the 5'S stereochemistry. In contrast, phosphite addition to the 2',3'-bis TBS protected aldehyde derived from ara-C gave only the 5'R adduct. However, TiCl(4)-mediated hydrophosphonylation of the same ara-C aldehyde favored the 5'S stereoisomer by a 2:1 ratio. Once all four of the diastereomers were in hand, the stereochemistry of these compounds could be assigned based on their spectral data or that obtained from their O-methyl mandelate derivatives. After hydrolysis of the phosphonate esters and various protecting groups, the four alpha-hydroxy phosphonic acids were tested for their ability to serve as substrates for the enzyme nucleoside monophosphate kinase and for their toxicity to K562 cells.

Synthesis and NMR Spectroscopic Study of a New Bis(aminophosphonate) with Terminal Furyl Groups

1,3-Bis[ N -methyl(diethoxyphosphonyl)-1-(2-furyl)]diaminobenzene has been synthesized through the addition of diethyl phosphite to the Schiff base N , N '-difurfurylidene- m -phenylenediamine. The compound has been characterized by elemental analysis, TLC, IR, and 1 H, 13 C, and 31 P NMR spectra. The NMR studies show that the reaction product is a mixture of two diastereomers ( meso and racemic forms). The 31 P NMR data revealed 61% content for the predominant and 39% for the minor form.

Double Asymmetric Induction During Addition of Chiral Phosphites to C=N Bond

Double Asymmetric Induction During Addition of Chiral Phosphites to C=N Bond

A One-Pot Procedure for the Synthesis of α-Amino Phosphonates from Alkynes

A new and highly flexible procedure for the synthesis of α,α-disubstituted α-amino phosphonates is described with disubstituted alkynes, primary amines and diethyl or dimethyl phosphite as starting materials. The reaction sequence, which is performed as a one-pot operation, starts with a Cp2TiMe2-catalyzed hydroamination of the alkyne. A subsequent nucleophilic addition of diethyl or dimethyl phosphite to the resulting imine, performed in the presence of catalytic amounts of Me2AlCl, gives the desired α-amino phosphonate. The application of intermolecular and intramolecular hydroamination reactions leads to the formation of both, cyclic and acyclic α-amino phosphonates.

Kinetics and mechanism of the pudovik reaction in the azomethine series: I. Addition of dimethyl hydrogen phosphite to N-isopropylbenzalimines

For a series of phenyl-substituted N-isopropylbenzalimines, the effect of substituent on their capability to add dimethyl hydrogen phosphite was studied qualitatively in the condensed phase (DTA) and quantitatively (with determination of the kinetic and activation parameters) in 2-propanol solutions with spectrophotometric monitoring of the reaction. A reaction mechanism was proposed, involving formation of a highly organized four-membered transition state.

Rationalization of the stereochemistry of an addition of dialkyl phosphites to certain chiral aldimines: The experimental and theoretical approach

AbstractThe absolute configuration of an α‐P stereogenic center in two diastereomeric O,O‐dialkyl α‐aminophosphonates (3), arising from an induced 1,3‐asymmetric phosphite addition to the CN bond of furfural‐derived Schiff bases (1), was established from single product 1H NMR data. Such spectra were interpreted with anisotropic shielding in relation to the AM1 and MNDO/d structures of 3; the former ones turned out to be closer to the obtained experimental results (1H NMR spectra of 3, crystallographic database study). Since favored 3‐21G geometries of starting imines 1 were modeled as well, it was inferred that a stereochemical outcome of this reaction is governed by Cram selectivity. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:120–125, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10005

Novel rapid‐cure adhesives for low temperature using thiirane compound

We investigated improvement of workability (viscosity), storage stability, and curing ability of thiirane resin for adhesive applications. The viscosity of bisphenol-F thiirane resin was lower than that of bisphenol-A thiirane resin, especially at low temperatures, thus improving ease of handling. Addition of diphenyl decyl phosphite improved its storage stability to a level similar to that of bisphenol-A epoxy resin. The curing of bisphenol-F thiirane resin increased three times faster by adding 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30) as a tertiary amine. In applications of this new thiirane resin as civil and architectural adhesives, a superior curing ability at low temperature was attained. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2953–2957, 2001

An expeditious one-pot synthesis of diethyl N-Boc-1-aminoalkylphosphonates

A general one-pot, purification-free synthesis of diethyl N-Boc-1-aminoalkylphosphonates has been developed. The procedure involves base-catalyzed Michael-type addition of sodium diethyl phosphite to N-Boc imines generated in situ by the action of sodium hydride on α-amidoalkyl- p-tolyl sulfones in tetrahydrofuran.

Stereochemistry of the addition of dialkyl phosphites to ( S)- N, N-dibenzylphenylglycinal

The addition of various dialkyl phosphite derivatives to ( S)- N, N-dibenzylphenylglycinal 6 led to the preponderance of anti over syn diastereoisomers: from 75:25 when NEt 3 or Ti(O iPr) 4 were used to 51:49 for Li or Mg salts. In the NEt 3-catalysed reaction, partially racemised phosphonates were formed, while enantiomeric products were obtained after addition of lithium O, O-dimethylphosphonate to ( S)- 6 at −70°C. Because the syn-isomers were found to be resistant to O-benzoylation, mixtures of diastereoisomers were easily separated after esterification of the anti products. Hydrogenation of the syn-phosphonates in the presence of Boc 2O gave enantiomeric dialkyl N-Boc-2-amino-1-hydroxy-2-phenylethylphosphonates—phosphonate analogues of the docetaxel C-13 side chain.

Asymmetric synthesis of beta-phosphono malonates via Fe2O3-mediated phospha-Michael addition to Knoevenagel acceptors.

[reaction: see text]. The first asymmetric P-C bond formation under heterogeneous conditions was achieved via a Fe2O3-mediated conjugate addition of a chiral phosphite to alkylidene malonates. The easy cleavage of the chiral auxiliary from the addition products leads to optically active beta-substituted beta-phosphono malonates in good yields and high enantiomeric excesses.

Novel rapid‐cure adhesives for low temperature using thiirane compound

AbstractWe investigated improvement of workability (viscosity), storage stability, and curing ability of thiirane resin for adhesive applications. The viscosity of bisphenol‐F thiirane resin was lower than that of bisphenol‐A thiirane resin, especially at low temperatures, thus improving ease of handling. Addition of diphenyl decyl phosphite improved its storage stability to a level similar to that of bisphenol‐A epoxy resin. The curing of bisphenol‐F thiirane resin increased three times faster by adding 2,4,6‐tris(dimethylaminomethyl)phenol (DMP‐30) as a tertiary amine. In applications of this new thiirane resin as civil and architectural adhesives, a superior curing ability at low temperature was attained. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2953–2957, 2001

The first synthesis of ferrocenyl aminophosphonic esters

The series of aminophosphonates bearing the ferrocenyl moiety was obtained by the addition of dialkyl phosphites to an azomethine bond of Schiff bases. Some successful attempts to perform the asymmetrical synthesis of aminophosphonates were made, but the isolation of diastereomers failed.

O‐Silyl Triflate‐Promoted Addition of Diethyl Phosphite to Chiral Aldonitrones. A Rapid Access to Complex α‐Amino Phosphonates and Their N‐Hydroxy Derivatives.

Abstract The addition reaction of diethyl phosphite to O-silylated N-benzyl nitrones derived from chiral α-alkoxy and N-Boc α-amino aldehydes has been studied as a stereoselective carbon phosphorus bond forming process for the synthesis of polyhydroxylated α-amino and α,β-diamino phosphonates. Key intermediates are the corresponding N-hydroxy α-amino phosphonates.

ChemInform Abstract: Asymmetric Synthesis of A‐Amino Phosphonic Acids via the Addition of Phosphites to Enantiopure Sulfinimines

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

O-Silyl triflate-promoted addition of diethyl phosphite to chiral aldonitrones. A rapid access to complex α-amino phosphonates and their N-hydroxy derivatives

The addition reaction of diethyl phosphite to O-silylated N-benzyl nitrones derived from chiral α-alkoxy and N-Boc α-amino aldehydes has been studied as a stereoselective carbonphosphorus bond forming process for the synthesis of polyhydroxylated α-amino and α,β-diamino phosphonates. Key intermediates are the corresponding N-hydroxy α-amino phosphonates.

Diastereoselective synthesis of α-substituted β-amidophosphonates

A simple and general asymmetric synthesis of β-amidophosphonates is described. The method involves the highly selective addition (up to 95% d.e.) of diethyl phosphite to various chiral α,β-unsaturated carboxylic amides derived from chiral aminoalcohols.

Addition of Dialkyl Hydrogen Phosphites to Alkenes in the Presence of Carbonyl Complexes of Chromium Subgroup Metals and Iron

Depending on the reactant ratio and order of their mixing, reactions of dialkyl hydrogen phosphite with alkenes in the presence of catalytic amounts of homoligand carbonyl complexes of iron or chromium subgroup metals yield phosphonates by two pathways: reaction of dialkyl hydrogen phosphite with π-coordinated alkene and addition to alkene of the product of reaction of dialkyl hydrogen phosphite with the transition metal carbonyl. The products of reactions of Fe(CO)5 and W(CO)6 with dialkyl hydrogen phosphites contain the phosphorus-metal bond.

α–βAlkenyl isomerisation at diiron centres

α-Substituted alkenyl complexes [Fe2(CO)6(μ-RCCH2)(μ-PPh2)] 1a–1e (R = Ph, Me, Prn, Bun or But) have been prepared via regioselective hydrodimetallation of primary alkynes by [Fe2H(CO)7(μ-PPh2)]. Thermolysis in toluene results in isomerisation to the β-substituted complexes [Fe2(CO)6(μ-HCCHR)(μ-PPh2)] 2a–2e. Isomerisation is accelerated in the presence of a range of tertiary phosphines yielding [Fe2(CO)5(PR′3)(μ-HCCHR)(μ-PPh2)] 3a–3e in which the phosphine is coordinated to the σ-bound metal centre and lies trans to the phosphido-bridge. Addition of trimethyl phosphite to [Fe2(CO)6(μ-PhCCH2)(μ-PPh2)] 1a at 60–70 °C affords mono- and di-substituted α-alkenyl complexes [Fe2(CO)5{P(OMe)3}(μ-PhCCH2)(μ-PPh2)] 4 and [Fe2(CO)4{P(OMe)3}2(μ-PhCCH2)(μ-PPh2)] 5 respectively. Above 100 °C, conversion into the β-substituted isomers [Fe2(CO)5{P(OMe)3}(μ-HCCHPh)(μ-PPh2)] 6 and [Fe2(CO)4{P(OMe)3}2(μ-HCCHPh)(μ-PPh2)] 7 occurs cleanly. Crystallographic studies have been carried out on 1a, [Fe2(CO)6(μ-PrnCCH2)(μ-PPh2)] 1c, [Fe2(CO)6(μ-HCCHPh)(μ-PPh2)] 2a, [Fe2(CO)5(PPh3)(μ-HCCHPh)(μ-PPh2)] 3a, 6 and 7 and compared with related structures. Different structural characteristics are seen between isomers, β isomers being characterised by a longer Feπ–Cβ interaction and a more obtuse Feσ–Cα–Cβ angle. The mechanisms of alkyne addition to [Fe2H(CO)7(μ-PPh2)] and alkenyl isomerisation have been probed using PhC2D. Hydrodimetallation results in an equal distribution of the deuterium over both β sites in 1a, and since they do not in exchange on the NMR timescale suggests that a radical process is operating. Thermolysis of this mixture leads to a 3∶1 mixture of [Fe2(CO)6(μ-DCCHPh)(μ-PPh2)] 2a-d1α and [Fe2(CO)6(μ-HCCDPh)(μ-PPh2)] 2a-d1β. A mechanism for α–β alkenyl isomerisation is proposed in which oxidative additions of the trans (exo) and cis (endo) β-protons to terminal sites on the diiron centre, giving a parallel alkyne intermediate, are in competition.

Enantioselective Addition of Dimenthyl and Dibornyl Phosphites to Schiff Bases

Enantioselective Addition of Dimenthyl and Dibornyl Phosphites to Schiff Bases