Gy. Keglevich

PHOSPHORYLATION OF PHENOLS AND NAPHTHOLS BY PHENYLMETHYLENEPHOSPHINE OXIDE GENERATED BY THE THERMOLYSIS OF A 2-PHOSPHABICYCLO[2.2.2]OCTA-5,7-DIENE 2-OXIDE

A simple method utilising a low-coordinate phosphorus species is described for the phosphorylation of a series of phenols and naphthols to afford aryl methylphenylphosphinates in reasonable yields.

Convenient Method for the Reduction of the Double-Bond of Cyclic Vinylphosphine Oxides Using Borane

Abstract The electronpoor double-bond of cyclic vinylphosphine oxides (1, 3 and 4) is easily reduced by borane in a selective manner to give the corresponding saturated derivatives (2, 4 and 5, respectively) Under forcing conditions, change of the functionality may also take place.

Selective phosphorylation of hydroxyphenols for forming reactive flame retardants

Monophosphorylated hydroxy phenols were synthesized in a selective way and incorporated in different percentages into epoxy resins as reactive flame retardants. The LOI values of the epoxy resin samples could be increased this way up to 28%. The DSC results show that by increasing the percentage of incorporated monophosphorylated hydroquinone (HMP), the exothermic effect of the curing is decreased, which implies lower network density. An optimum balance is necessary between the flame retardant effect, determined by percentage of HMP, and the lower degree of crosslinking.

The Effect of Silver Perchlorate of the Reaction of Trialkyl Phosphite with α-Halogenoketones

Abstract Trialkyl phosphites are known to react with α-halogenoketones to yield β-ketophosphonates (Arbuzov product) or vinyl phosphates (Perkow product) according to coniiitions.1 α-Hydroxyphosphonate may be formed in addition, in prcltic media.2 We have now shown that none of these products is formed in the presence of silver perchlorate (in benzene sclutim); nor could we detect the ketophosphonium perchlorate reported previously. Phosphorus-31 nmr showed the formation of trimethyl phosphate and tetramethyl pyrophosphate as the exclusive phosphorus-containing products. The sequence of possible reaction is complex and the overall stoichiometry may vary somewhat according to the rate and order of rixing. Trialkyl phosphate could be formed by elimination of alkyne from vinyloxyphosphonium intermediate produced together with silver iodine in first stage of the interaction. Pyrophosphate formation would then result from nucleophilic attack of trimethyl phosphate on the trimethoxy(1-nethylvinyloxy)phosphoniun...

The structure and spectroscopy of α-hydroxyphosphonates

Abstract α-Hydroxyphosphonates are important intermediates in the preparation of various organophosphorus compounds. Methods for their preparation have been described.1 We now report new aspects of their structure and spectroscopy. In the solid state, O,O-dimethyl α-hydroxy-α-phenyl-β-chloroethylphosphonate has been shown by X-ray diffraction studies to consist of hydrogen-bonded dimers with a hydrosen-bond length between the phosphoryl oxygen and hydroxyl hydrogen atom of 1.74 A. The P=0 bond is relatively short (1.463).

Products in the Reactions of Trialkyl Phosphites with α-Halogeno-acetophenones in Alcoholic Media

Abstract α-Hydroxyphosphonates are formed, in addition to vinyl phosphates and dehalogenated ketones, in the reactions of trimethyl phosphite (in methanol) or triethyl phosphite (in ethanol) with variously substituted α-chloro, α-bromo, and α,α,-dichloro-acetophenones. Tri-isopropyl phosphite in propan-2-ol gives only the vinyl phosphate. Ketophosphonates are not detectable amongst the reaction products under the conditions used. Trends in product composition can be correlated with the leaving ability of halogen, substituent effects, structure of the phosphite, and reaction temperature. Reactant ratios may also influence the product composition. The reactions of trimethyl phosphite in methanol with 4-nitro-α-chloroacetophenone, or α,α-dichloroacetophenones yield the dehalogenated α-hydrogxyphosphonates in addition. In the case of the 4-nitro derivative, this product cannot be accounted for by reaction of the phosphite with dehalogenated ketone (4-nitroacetophenone). Dehalogenation of the first-formed α-hy...

Crown Ethers in Enantioselective Synthesis

A research group at the Technical University, Budapest, has long been dealing with the synthesis and utilization of crown ethers and related molecules. A number of the sugar-based chiral crown ethers, as well as lariat ethers incorporating glucose, galactose, mannose and mannitol units in the hetero ring have been synthesized. The association constants of these compounds with Li + ,N a + ,K + and NH 4 + cations were measured, but the main point was to explore the possibilities offered by the chirality of the macrocycles. We wished to examine if the sugar-based crown ethers are capable for the discrimination of enantiomers and if they can bring about asymmetric induction as catalysts.

3J(P,C) Couplings in 3-Phosphabicyclo[3.1.0]Hexane 3-Oxides

Abstract Vicinal phosphorus-carbon carboncouplings (3J(P,C)) measured for 3-phosphabicyclo [3.1. O] hexane 3-oxides (1 and 2) of known geometry have been studied. With one exception (see below), the dependence of the 3J(P,C) constants on the torsion angles (⊘) followed the Karplus-equation (3J(P,C)=Acos2⊘+Bcos⊘+C).

Ring Enlargement of Phospholenes to Phosphorin Derivatives Through Dichlorocarbene Adducts

Abstract The ring enlargement of ready available phospholenes by dichlorocarbene addition to the double bond and subsequent opening of the cyclopropane ring is discussed. Adductcs of phospholene wih dichlorocarbene (2)can be synthetised under liquid-liquid phase transfer circumstances. The simplest bray to open the cyclopropane ring in the adducts is thermal transformation giving the two regioisomers of the appropriate dihydrophosphorin (3). Electrophilic reagents can also be used for -the opening of the cyclopropane ring. On heating with silver nitrate in water or in alcohols the adducts are transformed to the -two rcgioisomers of the hydroxy- or the alkoxy -tetrahydrophosphorins, respectively (4, Y=H, CH3 C2H5) In the reaction of adducts with mercury acetate-acetic acid the corresponding acetoxy-derivatives (4, Y=CH3CO) are formed. The Friedl Crofts reaction of the adducts with benzene iii the presence of aluminium trichloride yields diarylated product.

The Formation of Phosphacycloheptatrienes in Ring Enlargement Reaction

Abstract The forrmation of substituted phosphacycloheptatrienes in ring expansion reaction(s) is describzd. From thc: reac-tion of 3,4-dimethyl-l-phenyl-3-phospholene-l-oxide(1,R1 = c6H5, R2=R3 = CH3) with dichlorocarbene under liquid-liquid phase transfer circumstances not the expected adduct but the appropriate phoshacycloheptatrisne (4, Rl, R2,R3 as above) was prepared. The formation of this product can be explained assuming two ring expansions effected by two series of dichlorocarbene addition and cyclopropane ring opening. In the similar reaction of the methoxy-phospholenc derivative (1, R1=CH3O, R2 = R3 = CH3 four other products are also formed beside the phosphacyclohcptatriene. Again phosphacycloheptatrienes (4) are formed as the result of dichlorocarbene addition to the regioisoners of dihidrophosphorins (2) obtained from the phospholene-dichlorocarbene adducts by thermolysis. The same product can be derived from each regioisomeric pair.