Nucleophilic Fluorination of α‐Aroylphosphinates with Morpholinosulfur Trifluoride

Nucleophilic fluorination of aroyl‐phenyl‐phosphinates is highly dependent on the nature of the alkoxy substituents attached to the phosphoryl group. A reaction of aroyl‐phenyl‐phosphinates with morpholinosulfur trifluoride was shown to be a convenient synthetic method for high‐yield synthesis of α,α‐difluorobenzyl‐phenyl‐phosphinates using steric protection of the phosphoryl group by a bulky isopropoxy substituent. The methyl esters of aroylphosphinic acids in the same reaction conditions yield (fluoro‐diaryl‐methyl)‐pentafluorophosphates as the main reaction products.     

Inorganic coordination polymers. XII. Chromium(III) tris(phosphinates)

Cohesive films of a series of chromium(III) tris(phosphinates)[Cr(OPRR′O)(OPR″-R?O)(OPR^*R^**O)]_y in which the side groups on the phosphorus are alkyl, phenyl, and/or hydrogen groups have been prepared by reaction casting or by hot pressing. The preparative reaction appears to involve conversion of an aquahydroxo or hydroxo chromium(III) bis(phosphinate) to an intermediate hydroxo bis(phosphinate) containing coordinated phosphinic acid followed by an intrachain reaction leading to the tris(phosphinate). Tensile strengths of the chromium(III) tris(phosphinates) range from 100 to 5600 psi, elongations from less than 1 to 100%. Thermogravimetric data indicate that major decomposition occurs at temperatures from 200 to 435°C in air and from 410 to 510°C in nitrogen. Infrared spectra and physical properties are interpreted to support a structure for the chromium(III) tris(phosphinates) which is based on linear, triple-bridged chains. The presence of octyl or other long alkyl side groups on the phosphorus improves the physical properties, presumably by internal plasticization, but leads to decreased thermal stability.     

Asymmetric hydrogenation of enol phosphinates by iridium catalysts having N,P ligands

[reaction: see text] Enol phosphinates, which are structural analogues of enol acetates, have for the first time been employed as substrates for Ir-catalyzed asymmetric hydrogenation. A number of enol phosphinates have been synthesized and reduced successfully with up to and above 99% ee.     

NiCl2-catalyzed hydrophosphinylation

[reaction: see text] A new nickel-based catalytic system has been developed for phosphorus-carbon bond formation. The addition of alkyl phosphinates to alkynes is catalyzed by nickel chloride in the absence of added ligand. The reaction generally proceeds in high yields, even with internal alkynes, which were poor substrates in our previously reported palladium-catalyzed hydrophosphinylation of alkyl phosphinates. The method is useful for the preparation of H-phosphinate esters and their derivatives. The one-pot synthesis of various important organophosphorus compounds is also demonstrated. The reaction can be conducted with microwave heating.     

有机磷化合物的研究(Ⅵ)——氯代苯基的硫代膦酸酯和硫代次膦酸酯的合成

硫代膦酰氯和硫代次膦酰氯与取代酚(或它的钠盐)反应,可制得相应的酯类.本文合成了五种硫代膦酸酯和九种硫代次膦酸酯,均有一定的杀虫作用.     

A Synthetic Study of Chiral α‐Hydroxy‐H‐Phosphinates Based on Proline Catalysis

A highly enantioselective synthesis of α‐hydroxyphosphinates was achieved based on the L ‐proline‐catalyzed aldol reaction of α‐acylphosphinates and acetone. Due to the preexisting chirality at the phosphorus center, mixtures of two diastereomers of the α‐hydroxyphosphinates were obtained in moderate to good yields, with simultaneously high enantioselectivity for both diastereomers. The products could be converted into α‐hydroxy‐H‐phosphinates with satisfactory yields. Furthermore, an unprecedented oxidation–reduction reaction of the α‐hydroxyphosphinates or α‐hydroxy‐H‐phosphinates to form phosphonates was observed, and the mechanism involved in such a chemical transformation is discussed.     

Base-promoted O-deprotonation/alkylation reaction of P(O)–OH compounds with alkyl halides

A novel base-promoted O-deprotonation/alkylation reaction of P(O)–OH compounds with alkyl halides has been developed. The protocol is practical, representing a simple way to produce a broad spectrum of functionalized phosphinates, phosphonates, and phosphates from basic starting materials with good to excellent yields. A plausible mechanism was proposed for this reaction.     

Asymmetric hydrogenation of di and trisubstituted enol phosphinates with N,P-ligated iridium complexes

The iridium-catalyzed asymmetric hydrogenation of various di- and trisubstituted enol phosphinates has been studied. Excellent enantioselectivities (up to >99% ee) and full conversion were observed for a range of substrates with both aromatic and aliphatic side chains. Enol phosphinates are structural analogues of enol acetates, and the hydrogenated alkyl phosphinate products can easily be transformed into the corresponding alcohols with conservation of stereochemistry. We have also hydrogenated, in excellent ee, several purely alkyl-substituted enol phosphinates, producing chiral alcohols that are difficult to obtain highly enantioselectively from ketone hydrogenations.     

Dialkylaminoethylation of Trimethylsilyl Esters of Trivalent Phosphorus Acids

Abstract

Dialkylaminomethylation of trimethylsilyl esters of trivalent phosphorus acids using bis(dialkylamino)methanes was carried out for the first time. This reaction is a convenient method for preparation of quaternary coordinated phosphorus compounds, including dialkylaminomethyl and functional groups. Thus trimethylsilylphosphites and -phosphonites of various structures react with bis(dialklamino)-methanes according to Arbuzov reaction in the presence of zinc chloride as a catalyst, when heated to 120°C, resulting in formation of phosphonates and phosphinates (I)     

Synthesis and Biological Activities of Methyl 1-(5-Methyl Isoxazol-3-oxy Acetoxy) Alkyl Methyl Phosphinates

Methyl 1-(5-methyl isoxazol-3-oxy acetoxy) alkyl methyl phosphinates were synthesized by the condensation of O-methyl methyl 1-hydroxyalkyl phosphinates moiety with 5-methyl isoxazol-3-oxy acetyl chloride and were tested for plant growth regulatory activity and herbicidal activity. Some compounds exhibited notable plant regulatory activity and herbicidal activity.     

Enzymatic Resolution of Ethyl α-Hydroxyphosphinates in a Modified Reaction Environment

The enzymatic resolutions of two racemic ethyl hydroxyalkane(P-phenyl)phosphinates were performed by both esterification and hydrolysis approaches. The first reaction was performed in anhydrous diisopropyl ether with triethylamine or pyridine as additives by using lipases from three different sources (Candida cylindracea, Aspergillus niger, and Mucor javanicus). The increase in enantioselectivity was observed when NEt₃ was applied. The second reaction—lipase-catalysed hydrolysis of ethyl butyryloxyalkane(P-phenyl)phosphinates—was carried out by Candida cylindracea lipase in diisopropyl ether saturated with water or in aqueous solutions containing MgCl₂, LiCl, or Triton X-100. The usefulness of biphasic systems consisting of diisopropyl ether and water or aqueous solution of MgCl₂, LiCl, or Triton X-100 also were tested. The use of biphasic system in the presence of Triton X-100 resulted in the higher conversion of the substrates.     

1‐hydroxy‐1,1‐bis(H‐phosphinates): Synthesis,stability, and sorption properties

A synthesis of 1‐hydroxy‐1,1‐bis(H‐phosphinates) from acylchlorides is described. Solid‐state structures of two bis(phosphinates) determined by X‐ray diffraction showed variations in the P C distances. The compounds show negligible sorption on hydroxyapatite and an intermediate chemical stability in aqueous solution. The hydrolysis occurs in acidic as well as alkaline media. Hydrolysis rates of four derivatives show the lowest stability for aromatic derivatives as a result of the electron‐withdrawing effect. Main products of hydrolysis are 1‐hydroxy‐(H‐phosphinates) and phosphorous acid. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:195–201, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21003     

Synthesis of polymers containing tertiary phosphine oxides using complex bases

Tertiary phosphine oxides have been prepared in excellent yield from primary alkyl halides or aromatic halides and activated sodium phosphinates obtained by reaction of dialkyl phosphine oxides with complex bases (NaNH₂/tBuONa). This reaction has been successfully applied to soluble and cross-linked bromopolystyrenes and to macroporous polystyrenes with bromooctyl substituents giving polymers which contain pendant phosphine oxide groups.     

Base promoted synthesis of activated cyclopropanes bearing homologated carbonyl groups via tandem Michael addition-intramolecular enolate trapping

A simple base promoted intramolecular Michael initiated ring closure reaction of γ-hydroxyenone derived diphenyl phosphinates with 1,3-indandione, enabled the synthesis of novel activated cyclopropanes with homologated carbonyl moiety in good yield. Promising levels of enantioselectivity are achieved when using cinchona derivatives as promoters.     

The Hydrolysis of Phosphinates and Phosphonates: A Review

Phosphinic and phosphonic acids are useful intermediates and biologically active compounds which may be prepared from their esters, phosphinates and phosphonates, respectively, by hydrolysis or dealkylation. The hydrolysis may take place both under acidic and basic conditions, but the C-O bond may also be cleaved by trimethylsilyl halides. The hydrolysis of P-esters is a challenging task because, in most cases, the optimized reaction conditions have not yet been explored. Despite the importance of the hydrolysis of P-esters, this field has not yet been fully surveyed. In order to fill this gap, examples of acidic and alkaline hydrolysis, as well as the dealkylation of phosphinates and phosphonates, are summarized in this review.     

Synthesis of hydrophosphorylated fullerene under neutral conditions

[chemical reaction: see text]. A variety of phosphorous compounds such as secondary phosphines, phosphine oxides, phosphinates, and phosphonates undergo addition to [60]fullerene in DMSO/C6H5Cl without extraneous reagents to produce hydrophosphorylated fullerene derivatives in moderate to high yield.     

Asymmetric P−C Bond Formation: Diastereoselective Synthesis of Adjacent P,C‐Stereogenic Allylic Phosphorus Compounds

A novel catalytic asymmetric P?C bond formation between phosphinates/phosphine oxide and allylic carbonates was developed. This methodology could not only afford a variety of functionalized adjacent P,C‐stereogenic phosphorus compounds in high yields with high regio‐ and diastereoselectivities but also provide an alternative strategy to access enantiomerically enriched (S_P)‐phosphinates through kinetic resolution.     

Allylic phosphates and allylic phosphinates as electrophiles in efficient silylcupration reactions of acetylenes

Atom-efficient stoichiometric silylcupration reactions of acetylenes followed by electrophilic trapping of the intermediate vinylcopper species with allylic phosphates have been developed. The reaction sequence was also carried out with the use of a catalytic amount of CuCN employing of both allylic phosphates and allylic phosphinates as electrophiles. The methods developed provide an easy access to silylated 1,4-diene systems.     

Synthesis of alkyl α‐aminomethyl‐phenylphosphinates and N,N‐bis(alkoxyphenylphosphinylmethyl)amines by the microwave‐assisted Kabachnik–Fields reaction

As a novel extension, the Kabachnik–Fields reaction was applied to the synthesis of alkyl α‐aminomethyl‐phenylphosphinates, and the double phospha‐Mannich reaction was utilized in the preparation of bis(alkoxyphenylphosphinylmethyl)amines. A total of 27 new aminophosphinate derivatives were synthesized by the microwave‐assisted solvent‐free condensation of alkyl phenyl‐H‐phosphinates, paraformaldehyde, and primary or secondary amines. The starting P‐species were also prepared under microwave conditions. The formation of the N‐methylated aminomethyl‐phenylphosphinate by‐products was also investigated.     

Microwave-assisted neat synthesis of α-aminophosphonate/phosphinate derivatives of 2-(2-aminophenyl)benzothiazole as potent antimicrobial and antioxidant agents

A series of diethyl/ethylphenyl {2-(benzo[d]thiazol-2-yl)phenylamino}phosphonates and phosphinates were synthesized under microwave irradiation and neat conditions via Kabachnik-Fields reaction in high yields (80%–93%). The compounds were screened for antimicrobial and antioxidant properties. A few compounds showed effective antibacterial and antifungal activities at MIC value 12.5 μg/mL as compared with the standard at MIC value 6.25 μg/mL.