The Behavior of 3,4,5-Trimethoxybenzylidenemalononitrile Towards Alkyl Phosphites

3,4,5-Trimethoxybenzylidenemalononitrile 1 reacts with trialkyl phosphites 2a-c in the absence of solvent to give the phosphonate derivatives 4a-c . The dimeric compound 6 also was produced in the reaction with 2c . The phosphonates 8a-c were produced when compound 1 was allowed to react with dialkyl phosphites 3a-c under the same experimental conditions. A mechanism is proposed to explain the formation of compounds 4 and 6 .     

Coupling Reactions of Heteroarenes with Phosphites under Silver Catalysis

A silver-catalyzed dehydrogenative cross-coupling reaction of substituted furans, thiophene, thioazole, and pyrrole 1a-e with dialkyl phosphites 2 was first developed to afford corresponding phosphonated products 3a-h with up to 89% yield and good regioselectivities. Moreover, an unprecedented coupling of various substituted pyridines 1f-k with dialkyl phosphites 2 using AgNO(3) as a catalyst and K(2)S(2)O(8) as an oxidant, followed by reduction with Na(2)S(2)O(3), was also realized to furnish desired pyridine phosphonates 3i-q in satisfactory yields with good regioselectivities.     

Organophosphorus Chemistry 34 1 . The Reaction of Alkyl Phosphites and Hexamethylphosphorus Triamide with 1-Phenyl-3-methyl-4-ylidene-5-pyrazolones

1-Phenyl-3-methyl-4-ylidene-5-pyrazolones ( 1a-c ) produce the respective 1:1 phosphonate adducts ( 4a-i ) upon reaction with the appropriate dialkyl phosphites ( 2a-c ). The reaction of 1a-c with trialkyl phosphites ( 3a-c ) proceeds only in presence of water, also to give phosphonates 4a-c almost exclusively. Hexamethylphosphorus triamide ( 3d ) was successfully utilized to introduce the bis(dimethylamino)-phosphoryl function in the f , g -unsaturated carbonyl moiety in 1a-c , producing phosphoramidates 15a-c . Possible reaction mechanisms were discussed. Compatible elemental and spectroscopic results were recorded for the new products.     

Solvent-free reaction of some 1,2-diaza-1,3-butadienes with phosphites: environmentally friendly access to new diazaphospholes and E-hydrazonophosphonates

[structures: see text] The present article describes the reaction between 1,2-diaza-1,3-butadienes and trialkyl phosphites, under an atmosphere of nitrogen and under solvent-free conditions, to give alkyl 3,3-dialkoxy-2H-1,2,3lambda5-diazaphosphole-4-carboxylates that, in turn, are converted into corresponding E-hydrazonophosphonates by treatment with THF:water (95:5). These latter compounds are obtained directly by the reaction of 1,2-diaza-1,3-butadienes with trialkyl phosphites in the presence of air. These compounds are useful for the further preparation of dialkyl (5-methyl-3-oxo-2,3-dihydro-1H-4-pyrazolyl)phosphonates and 2-dialkoxyphosphoryl-1,2,3-thiadiazoles.     

Mild and efficient Cs2CO3-promoted synthesis of phosphonates

A mild and convenient synthesis for phosphonates using cesium carbonate (Cs₂CO₃), tetrabutylammonium iodide (TBAI) and DMF was developed at room temperature. Numerous dialkyl phosphites were screened using a diverse array of alkyl halides and these reaction conditions were found to be highly efficient producing various phosphonates exclusively in moderate to high yields.     

Synthesis and Biological Activity of O,O′-Dialkyl 5-Aryl-1-Hydroxy-3-Methyl-2E,4E-Pentadienylphosphonates

A series of unsaturated f -hydroxy phosphonates were synthesized by the addition reactions of dialkyl phosphites with 5-aryl-3-methyl-2E, 4E-pentadienaldehydes. The structures of all new compounds have been confirmed by 1 H NMR, 31 P NMR, and IR spectroscopy and by elemental analysis or MS. The bioassays showed that some of these compounds exhibit certain inhibitory activity on the elongation of wheat coleoptile.     

Simple and Advantageneous Stereoselective Synthesis of (Z)-Allyl Phosphonates Starting from Baylis–Hillman Adducts

Baylis–Hillman adducts 3-hydroxyl-2-methylene alkanoates have been converted in one pot into the corresponding (Z)-allyl phosphonates by treatment with FeCl₃ and trialkyl phosphites in toluene under reflux. The products are formed in excellent yields (88–98%) within 1–1.5 h. The process is highly convenient and efficient, cost-effective, and remarkably stereoselective.     

Improved facile synthesis of α-amino phosphonates by the reaction of α-amido sulfones with dialkyl trimethyl silyl phosphites catalyzed by Fe(III) chloride

An improved efficient synthesis of α-amino phosphonates has been discovered by the reaction of N-benzyloxycarbonylamino sulfones with dialkyl trimethyl silyl phosphites in the presence of FeCl₃ as a catalyst. The products were formed in high yields (86–94%) within 2–4?h. The catalyst is inexpensive, easily available, and highly active. The unreacted dialkyl trimetyl silyl phosphites can easily be removed from the products due to their low boiling points. The sulfones can conveniently be prepared and are generally stable.     

Concept of improved rigidity: how to make enantioselective hydrophosphonylation of cyclic imines catalyzed by chiral heterobimetallic lanthanoid complexes almost perfect

The catalytic and enantioselective hydrophosphonylation of cyclic imines using cyclic phosphites is described for the first time. In contrast to the application of acyclic phosphites, significant improvements are presented arising from the concept of improved rigidity by utilization of cyclic phosphites in the lanthanoid BINOL complex catalyzed hydrophosphonylation of 3-thiazolines. Cyclic phosphites are shown to provide certain improvements within the catalytic cycle. Influence of parameters such as concentration of the catalyst and the phosphite on the catalysis is examined as well as the effects of the substituents on the starting material. The pharmacologically interesting thiazolidinyl phosphonates are synthesized in excellent optical purities of up to 99% ee and high chemical yields of up to 99%. The required amount of catalyst is reduced to 2.5 mol %. The highest efficiency of the reaction involving cyclic phosphites is achieved using the catalytic system "2.5 mol % (S)-YbPB/2.5 equiv phosphite/50 degrees C/48 h/THF-toluene (1:7)". On the basis of the results a refinement of the proposed catalytic cycle has been provided. For comparison cyclic phosphites were used in hydrophosphonylation with a chiral titanium catalyst.     

The Reactivity of Hexafluorothioacetone and Hexafluoroacetone versus Phosphites

Abstract

The dimer of hexafluorothioacetone reacted with various phosphites to form thiophosphates and bis(trifluoromethyl)methylenphosphoranes, being unstable in the case of (Me₃SiO) P(OMe)_3-n, (n=1?3), where phosphonates (Me₃SiO)_n-1(MeO)_3-nP(O)[C(CF₃)=CF₂] (n=1-3) and Me₃SiF were observed. In general, cyclic phosphites behaved similar to acyclic ones. The resulting bis(trifluoromethyl)methylenphosphoranes were thermally stable except compound A, because of a new intramolecular fluorine transfer to phosphorus forming fluorophosphorane B.     

Synthesis of Some Dialkyl Bromo-Substituted Benzyl Phosphonates

Arbuzov reaction of bromo-substituted benzyl bromides and trialkyl phosphites in benzene gave high yields of dialkyl bromo-substituted benzyl phosphonates, and —CH₂CH₂CH₂CH₃). The structural assignments of these phosphonates were confirmed by ¹H nmr, ¹³C nmr, ir and mass spectral analysis.     

The first synthesis of β-amino phosphonates using cyclic sulfamidates

Cyclic sulfamidates (prepared from α-amino acids and β-amino alcohols) have been used for the first time for the synthesis of novel β-amino phosphonates (chiral and achiral) by treatment with dialkyl phosphites using sodium hydride. 2-Substituted and 1,2-disubtituted β-amino phosphonates have efficiently been prepared following this method. The products are formed in high yield (79-84%) within 8-12 h.     

Base-controlled reaction of α,β-unsaturated trifluoromethyl ketone and dialkyl phosphite

Base-controlled selective reactions of α,β-unsaturated trifluoromethyl ketones with dialkyl phosphites were achieved. In the presence of DABCO, the Pudovik reaction took place readily to give the corresponding α-hydroxy phosphonates in high yields under mild conditions. While using DBU as base, the Phospha-Brook rearrangement of α-hydroxy phosphonates formed in the reaction occurred to afford phosphates as final products.     

New Unusual Reactions in the Chemistry of Unsaturated Organophosphorus Compounds

Abstract

Arbusov reaction of trialkyl phosphites with haloalkynes opened a new route to the synthesis of acetylenic phosphonates as well as attracted the investigators attention to the nucleoohilic substitution of halogene at sphybridized carbon atoms. The most important compounds of this type are chloro- and bromoethyne phosphonates formed by the action of dihaloethynes upon phosphites. These polyfunctional compounds may interact via triple bond opening and/or halogene substitution. The latter pathway results in the formation of different phosphonates and diphosphonates (1):      

The behavior of 2‐thioxo‐4‐thiazolidinones toward organophosphorus reagents

The reaction of 2‐thioxo‐4‐thiazolidinone ( 1a ) with phosphorus ylides 2a and 2b afforded compounds 5 and 6. On the other hand, formylmethylenetriphenylphosphorane (2c) reacts with 1a and its N‐methyl derivative 1b to give the new complicated phosphonium ylides 7a,b, respectively. Reactions of 1b with ylides 2a and 2d gave rise to the olefinic compound 8 and the new phosphorane product 9. Moreover, dialkyl phosphites 3a,b and trialkyl phosphites 4a–c react with 1a to give both the alkylated products 10a–c and the dimeric compounds 11,12. A mechanism is proposed to explain the formation of the new products.© 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 337–341, 1999     

Isosteviol acylphosphonates

A reaction of ent-16-oxobeyeran-19-oic acid (isosteviol) with an excess of PCl3 gives the corresponding acid chloride as a sole product. The latter reacts with trialkyl phosphites and dialkyl trimethylsilyl phosphites to yield acylphosphonates inert to nucleophilic reagents.     

Organophosphorus esters—IV : Novel approach to monoalkyl hydrogen phosphites

Tetramethylammonium t-butyl hydrogen phosphite (2), readily available from the reaction between di-t-butyl phosphite and aqueous tetramethylammonium hydroxide, was found to be a convenient phosphorylating agent for organic halides. It reacts easily with alkyl iodides and some alkyl bromides in boiling acetone affording the corresponding alkyl t-butyl phosphites (3). On treatment with trifluoroacetic acid at room temperature these compounds can be readily converted into monoalkyl hydrogen phosphites (1), isolated and characterized as S-p-chlorobenzylthiouronium derivatives (4).     

Sulfinimine-mediated asymmetric synthesis of beta-hydroxy alpha-amino phosphonates

The addition of potassium dialkyl phosphites to enantiopure O-protected alpha-hydroxy sulfinimine pseudoenantiomers affords beta-hydroxy alpha-amino phosphonates in good yield and de. The reaction exhibits a strong match-mismatch effect.     

Al(H_2PO_4)_3 as an Efficient and Reusable Catalyst for One-pot Three-component Synthesis of α-Amino Phosphonates under Solvent-free Conditions

Synthesis of α‐amino phosphonates is described under solvent‐free conditions at 100°C from reaction between aldehydes and amines in the presence of trialkyl phosphites using Al(H₂PO₄)₃ as an efficient and reusable heterogeneous catalyst. The advantages of this procedure are short reaction time, flexibility and having high to excellent yields.     

Organophosphorus chemistry 23 [1], the reaction of α,β-unsaturated nitriles with alkyl phosphites and phosphorus ylides

Wittig reagents 2 react with furfurylidenemalonitrile ( 1a ) and thienylidenemalonitrile ( 1b ) to give a mixture of products ( 6 and 7 ). Compound 1b reacts with di-alkyl phosphites ( 3 ) and trialkyl phosphites ( 4 ) to give the phosphonate 1:1 adducts 9 and 12 , respectively. Structures of the new products were confirmed on the basis of elemental analyses and spectral studies.