Cyclic Phosphites Research Articles

The Stereochemical Course of the α-Hydroxyphosphonate-Phosphate Rearrangement.

The phosphonate–phosphate rearrangement is an isomerisation of α-hydroxyphosphonates bearing electron-withdrawing substituents at the α-carbon atom. We studied the stereochemical course of this rearrangement with respect to phosphorus. A set of four diastereomeric α-hydroxyphosphonates was prepared by a Pudovik reaction from two diastereomeric cyclic phosphites. The hydroxyphosphonates were separated and rearranged with Et3N as base. In analogy to trichlorphon, which was the first reported compound undergoing this rearrangement. All four hydroxyphosphonates could be rearranged to 2,2-dichlorovinyl phosphates. Single-crystal X-ray structure analyses of the α-hydroxyphosphonates and the corresponding phosphates allowed us to show that the rearrangement proceeds with retention of configuration on the phosphorus atom.

ChemInform Abstract: The Kabachnik—Fields Reaction: Mechanism and Synthetic Use

AbstractReview: 51 refs.

Bulky monophosphite ligands for ethene hydroformylation

A wide range of monophosphite ligands was investigated in rhodium-catalyzed ethene hydroformylation. A stoichiometric gas mixture CO/H2/ethene 1:1:1 was used, the reaction being thus 100% atom economic. The reaction was found to be very selective and only propanal was formed under the reaction conditions studied. The most efficient catalytic system was L1-modified rhodium, and reaction parameters were optimized for this ligand. Under optimized catalytic conditions, reaction rates 10–15 times higher than those of the triphenylphosphine-modified system were obtained, demonstrating the high suitability of π-accepting ligands for this reaction. Stability tests, resistance toward water and acids in particular, showed the good stability of the selected phosphite L1. Notably, L1 was more stable than cyclic phosphites L6 and L13.

Novel Rearrangement of Spirophosphoranes

Reactions of N-trifluoroacetyl trifluoroacetimidoyl chloride with acyclic or cyclic phosphites proceed by the cheletropic 1,4-cycloaddition scheme to form mono- or spirocyclic phosphoranes. The spirophosphorane resulting from the reaction with diethylamino-o- phenylenedioxyphosphite undergoes unusual acid catalyzed stereoselective rearrangement involving ring expansion to afford functionalized cyclic aminophosphonate.

Determination of absolute configuration of the phosphonic acid moiety of fosfazinomycins

Fosfazinomycins A and B produced by Streptomyces lavendofoliae share the same phosphonate moiety with one chiral centre of unknown configuration which was determined by synthesising both enantiomers of 2-hydroxy-2-phosphonoacetic acid methyl ester. A chiral cyclic phosphite was reacted with methyl glyoxylate in a Pudovik reaction to give a pair of diastereomeric α-hydroxyphosphonates, which were separated by HPLC. The configurations at C-2 were assigned on the basis of single crystal X-ray structure analysis. Deprotection of these diastereomers furnished the enantiomeric α-hydroxyphosphonic acids, of which the (S)-configured had the same sign of optical rotation as the phosphonic acid moiety of the two fosfazinomycins.

The Kabachnik–Fields Reaction: Mechanism and Synthetic Use

The Kabachnik–Fields (phospha-Mannich) reaction involving the condensation of primary or secondary amines, oxo compounds (aldehydes and ketones) and >P(O)H species, especially dialkyl phosphites, represents a good choice for the synthesis of α-aminophosphonates that are of significant importance due to their biological activity. In general, these three-component reactions may take place via an imine or an α-hydroxy-phosphonate intermediate. The monitoring of a few Kabachnik–Fields reactions by in situ Fourier transform IR spectroscopy has indicated the involvement of the imine intermediate that was also justified by theoretical calculations. The Kabachnik–Fields reaction was extended to >P(O)H species, comprising cyclic phosphites, acyclic and cyclic H-phosphinates, as well as secondary phosphine oxides. On the other hand, heterocyclic amines were also used to prepare new α-amino phosphonic, phosphinic and phosphine oxide derivatives. In most cases, the synthesis under solvent-free microwave (MW) conditions is the method of choice. It was proved that, in the cases studied by us, there was no need for the use of any catalyst. Moreover, it can be said that sophisticated and environmentally unfriendly catalysts suggested are completely unnecessary under MW conditions. Finally, the double Kabachnik–Fields reaction has made available bis(phosphonomethyl)amines, bis(phosphinoxidomethyl)amines and related species. The bis(phosphinoxidomethyl)amines serve as precursors for bisphosphines that furnish ring platinum complexes on reaction with dichlorodibenzonitriloplatinum.

ChemInform Abstract: The Asymmetric Synthesis of Chiral Cyclic α‐Hydroxy Phosphonates and Quaternary Cyclic α‐Hydroxy Phosphonates.

AbstractA dialuminum complex derived in situ from chiral tridentate Schiff Base TSB in combination with silver carbonate catalyzes the addition of cyclic phosphite (II) to aldehydes or ketones to give the title phosphonates with up to 99% enantioselectivity.

The asymmetric synthesis of chiral cyclic α-hydroxy phosphonates and quaternary cyclic α-hydroxy phosphonates

A highly practical, catalytic enantioselective cyclic phosphite addition to aldehydes and ketones was developed. The reaction rate of the asymmetric hydrophosphonylation was significantly enhanced by the addition of silver carbonate. Particularly, significant improvement has been achieved on the asymmetric hydrophosphonylation of unactivated ketones, giving quaternary α-hydroxy phosphonates with excellent enantioselectivity (up to 99% ee).

Phosphorus-bridged calixarene phosphites: dramatic influence of a tert-butyl group at the upper rim of the macrocycle upon anion binding

New cyclic phosphite derivatives of calix[4]arenes in 1,2-alternate configuration were obtained by the interaction of calix[4]arenes with ethylene chlorophosphite; the influence of a tert-butyl group at the upper rim of the macrocycle upon anion binding was shown

ChemInform Abstract: New Aspects in the Chemistry of Some Cyclic Esters of Alkylphosphonates.

Abstract Several new methods for the synthesis of 2-alkyl-2-oxo-1,3,2-dioxa-phosphorinane (1) and -phosphepane (2) were conducted based on Arbuzov rearrangement, alcoholysis of RP(o)Cl2 with glycol using dilution method or alkylation of cyclic phosphite under PTC condition. The solvent effect on the 31P NMR chemical shift and the characteristic behaviours of the 13C NMR spectra of 1 was investigated. It was found that compd 1 with R=CH3 existed in an equilibrium of e and a forms. The mass spectra of 1 and 2 showed that the ring opening was in competition with the cleavage of P-C bond. According to the fragmentation pathway, 1 can be classified in two categories involving ring opening and cleavage of C-C or P-C bond. For compd 2 the ring opening was a dominant process. Alkaline hydrolysis of 1 and 2 was studied in aqueous dioxane. The hydrolytic process is classified as an AE reaction. Quantitative structure-reactivity relationship was established by multiple regressionanalysis involving the rate constant ...

ChemInform Abstract: Synthesis of α-Vinylidene-β-lactams by the Palladium- Catalyzed Carbonylation of 4-Amino-2-alkynyl Carbonates.

Abstract The palladium-catallyzed carbonylation of 4-amino-2-alkynyl carbonates proceeded under mild conditions to afford α-vinylidene-β-lactams in moderate yields. The cyclic phosphite, 4-ethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane was found to be the best ligand.

New data in the chemistry of phosphotrimethylenepentaerythritol

Unsymmetrical trimethylene diol was obtained at the transacetalation of dimethoxymethane with tripentaerytritol. On the basis of the diol a group of acyclic and cyclic phosphites interesting as ligands for the metallocomplex bioregulators with sophisticated structure were synthesized.

Thermochemistry of heteroatomic compounds 26.* Calculation of the combustion and formation enthalpy of carbohydrate bicyclophosphites

The enthalpies of combustion for five noncyclic and cyclic phosphites in the condensed state were calculated from the derived equation ΔHcomb/kJ mol-1 = —860.7 — 107.0(N — n), where N is the number of bonding valent electrons, and c is the number of lone electron pairs of heteroatoms. The dependence presented was used to calculate the combustion enthalpy of five phosphorylated carbohydrates, because these thermochemical values are often difficult to determine by reaction calorimetry. The enthalpies of formation of carbohydrate cyclophosphites were calculated by Hess’s law for the first time.

α-Fluorinated cyclic amidophosphite ligands. Their synthesis, Rh complexes and catalytic activity in the hydroformylation of styrene

The synthetic approaches to cyclic phosphite and amido(diamido)phosphite ligands bearing the residues of electron withdrawing perfluorinated tails at the β-position to the phosphorus atom have been elaborated. Catalytic systems based on rhodium complexes of these ligands formed in situ using Rh(CO) 2(acac) as a catalytic precursor demonstrate high activity in the hydroformylation of styrene along with good selectivity in respect to branched aldehyde. Quantum-chemical calculations proved that both the rate of the formation of branched alkyl complex, as well as its reactivity are influenced by the steric and electronic parameters in the same manner.

The Effect of Trifluoroethoxy Groups on the Structures of Eight-Membered Ring-Containing Cyclic Phosphites1

New phosphites 1–4 were synthesized from phosphorus trichloride and an appropriate diphenol followed by the addition of trifluoroethanol in the presence of triethylamine. These phosphites are to serve as precursors in the syntheses of biorelated hypervalent phosphoranes. 1H, 19F, and 31P NMR spectra were recorded. X-ray analysis of 3 and 4 revealed that the sulfur-containing eight-membered ring was in a syn conformation that a allowed a sulfur donor interaction to the phosphorus atom, whereas for phosphite 2, the eight membered sulfonyl containing ring was in an anti conformation that did not allow a donor interaction to phosphorus from the oxygen atom of the sulfonyl group. Structural comparisons are made with related cyclic phosphites and phosphates having donor atoms in eight-membered rings.

2-Hydroxymethyl-2-propyl-1,3-propanediol in the Synthesis of Phospholipids

New representatives of nonglycerol polyol phospholipids were synthesized from 2-hydroxymethyl-2-propyl-1,3-propanediol through intermediate phosphoramidites and cyclic phosphites obtained from isopropylidene derivative of the title triol. Treatment of these intermediate products with sulfur or selenium afforded the corresponding thio- and selenophosphates which were converted into lipids by direct acylation with higher carboxylic acid chlorides.

Novel α-fluorinated cyclic phosphite and phosphinite ligands and their Rh-complexes as suitable catalysts in hydroformylation

Asymmetrical cyclic phosphite and phosphinite ligands of a novel type bearing either trifluoromethyl or pentafluorophenyl group were synthesized using >PCl or >PN< species and racemic fluorinated alcohols. The P-ligands were converted to complexes of RhIII(L)(Cp∗)Cl2 type (where L=phosphite or phosphinite) and, in two instances, their stereostructures were evaluated by X-ray analysis. These complexes along with in situ systems, formed from Rh(CO)2(acac) precursor and the corresponding ligand, were tested in the hydroformylation of styrene. Both systems provided excellent hydroformylation activities at 100 °C. Using the RhI in situ systems, moderate and high regioselectivities towards the branched aldehyde (2-phenyl-propanal) were obtained at 100 and 40°C, respectively.

Synthesis of 2‐phosphinoxidomethyl‐ and 2‐phosphonomethyl glutaric acid derivatives

AbstractMichael addition of the corresponding anions derived from diphenylphosphine oxide, dialkylphosphites, and a cyclic phosphite to α‐methylene‐glutaric esters (1) afforded the title compounds (2–6). Double debenzylation of 2‐phosphono glutaric esters 4b and 5a by catalytic hydrogenation under the appropriate conditions gave the correspon‐ ding diacides 8 and 9, respectively. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:562–565, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20142

Chiral Bis(N-sulfonylamino)phosphine- and TADDOL-Phosphite-Oxazoline Ligands: Synthesis and Application in Asymmetric Catalysis

A series of N,P-ligands has been prepared, containing a chiral oxazoline ring and as a second chiral unit a bis(N-sulfonylamino)phosphine group embedded in a diazaphospholidine ring or a cyclic phosphite group derived from TADDOL. These modular ligands are readily synthesized from chiral amino alcohols and chiral 1,2-diamines or TADDOLs. Palladium and iridium complexes derived from these ligands were found to be efficient catalysts for enantioselective allylic alkylation and olefin hydrogenation, respectively.

Cationic Phospholipids on the Basis of Higher Fatty Alcohols

A perspective synthetic approach to cationic amidodiester lipid constructions on the basis of cyclic phosphites derived from octadecan-1-ol is presented. The syntheses of phospholipids were carried out by oxidative decyclization of cyclic phosphoramidites with bromine.