Imre Petneházy

Phosphite Addition to Carbonyl Group and Phosphoryl Migration Under Phase Transfer Catalytic Circumstances

Abstract The rearrangement of α-hydroxyphosphonates to phosphates under PTC conditions usually run in a different way and gives better yield as that found in homogenous system.

Antagonistic reactions of arginine and lysine against formaldehyde and their relation to cell proliferation, apoptosis, folate cycle and photosynthesis

Abstract1H, 13C NMR, ESMS and MS/MS investigations proved that there is an antagonism in the spontaneous reaction of formaldehyde with L-lysine and L-arginine. L-Arginine can only be hydroxymethylated on the guanidino group in a very fast reaction forming mono-, di-, and trihydroxymethyl arginines (HMA). L-Lysine can be methylated on the ε-amino group forming mono-, di-, and trimethyl lysine on physiological pH. Hydroxymethyl arginines are relative stable, isolable products, and can also be formed in biological systems, especially in plants. Significant amounts of hydroxymethyl arginines were identified in the aqueous extract of lyophilized kohlrabi, which can be formed in photosynthesis during CO2 fixation. 14C-Formaldehyde formed in a short-term (10, 30 sec) 14CO2 fixation reaction in Zea mays L. (early maturity variety: Szegedi TC 277) was captured by L-arginine, which occurs in leaves in large amount. Formaldehyde formed during photosynthesis can react not only with the arginine, but with ribulose-1,5-diphosphate present in leaves. In model reactions formaldehyde can react with the ‘ene diole’ group of ribulose-1,5-diphosphate in the absence of Rubisco enzyme, which is a similar reaction to the addition of formaldehyde to L-ascorbic acid. Hydroxymethyl arginines (HMA) are endogenous formaldehyde carrier molecules transferring the bound formaldehyde to thymidylate synthase enzyme system incorporating it into the folate cycle. HMA can also carry the bound formaldehyde to the cells especially to the tumorous cells (HT29 adenocarcinoma), and cause significant inhibition of cell proliferation and causes apoptosis.

A versatile building block for the synthesis of substituted cyclopropanephosphonic acid esters

Abstract By the effect of iodine, solid K 2 CO 3 and a lipophilic quaternary ammonium salt phosphonoacetic acid allylic esters 4 were converted to cyclopropanephosphonic acid derivatives anellated to a five membered lactone ring 6 serving as good starting material for biologically active products. The reaction of cyclopropanation has been assumed to proceed by SET induced radical type elemental steps. Direct evidences were given by ESR for the 6-endo regioselectivity in the closure of electrophilic radical 11 . An interesting and new exchange reaction of phosphonic ester moiety by iodine is also observed.

The first enantioselective synthesis of α-aminophosphinates

The first enantioselective synthesis of substituted α-aminophosphinic acids was carried out by the addition of ethyl phenylphosphinate to chiral imines in the absence of base or other catalyst.

CHEMICAL SHIFT NON-EQUIVALENCE IN THE NMR SPECTROSCOPY OF DIALKYL α-HYDROXYBENZYL-AND DIALKYL α-METHOXYBENZYLPHOSPHONATES AND THE CRYSTAL STRUCTURE OF DIMETHYL α-CHLOROMETHYL-αHYDROXYBENZYLPHOSPHONATE

Abstract Single crystal X-ray diffraction of dimethyl α-chloromethyl-α-hydroxybenzylphosphonate shows the compound to exist as hydrogen-bonded dimers in the solid state. In solution, 1H and 13C nmr spectroscopy reveal chemical shift non-equivalence of the corresponding nuclei in the two alkoxy groups of dialkyl α-hydroxybenzyl-and dialkyl α-methoxybenzylphosphonates, an effect that is attributed primarily to the presence of the chiral α-carbon atom, although restriction of rotation about the P—C α bond by intermolecular hydrogen-bonding may also be a factor in the α-hydroxy compounds. Chemical shift non-equivalence of the α-halogenomethyl protons in dimethyl α-halogenomethyl-α-hydroxyben-zylphosphonates is significantly greater for the chloro-than for the bromo-compound.

Quantitative structure-electrochemistry relationships of α, β-unsaturated ketones

Abstract The half-wave potential ( E 1 2 ) of 26 substituted α,β-unsaturated ketones in non-aqueous acetonitrile were used in Hammett type quantitative structure-activity relationship (QSAR) analysis. A linear relationship between E 1 2 and the electronic substituent constant, σx and reaction constant grR was revealed for 17 substituted chalcones. Linear regression equations were calculated using only the sum of σx,para + σx,meta of all substituents. It was found that the production of the substituted 1,2-oxaphosphol-4-en in the redox reaction of the α,β-unsaturated ketones and trialkyl phosphite can be predicted from the E 1 2 values of the α,β-unsaturated ketones measured in nonprotic solvent. The E 1 2 values also give a linear correlation with the conversions of the starting ketones.

Quasiphosphonium intermediates—IV: Isolation and identification of intermediates in the arbuzov and perkow reactions of neopentyl esters of phosphorus(III) acids with α-halogenoacetophenones

Abstract Crystalline ketophosphonium bromides have been isolated as intermediates in the reactions of trineopentyl phosphite, dineopentyl phenylphosphonite, and neopentyl diphenylphosphinite with α-bromoacetophenone. Thermal decomposition in solution occurs in each case to yield neopentyl bromide and the corresponding Arbuzov product only. Rearrangement to the Perkow intermediate or product does not occur. An identifiable Perkow intermediate was separated from the reaction of neopentyl diphenylphosphinite with α-chloroacetophenone at O° and was shown to yield neopentyl chloride and the corresponding Perkow product by a first-order process in chloroform (t 1 2 ca 40min at 33°). It is suggested that the betaine formed by initial attack of phosphorus at the carbonyl carbon atom may be a common first intermediate in reactions that yield both Arbuzov and Perkow products

FACTORS IN THE CONTROL OF PRODUCT COMPOSITION IN THE REACTIONS OF TRIALKYL PHOSPHITES WITH α-HALOGENOACETOPHENONES 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. Additional products are obtained in the reactions of trimethyl phosphite in methanol with 4-nitro-α-chloroacetophenone, which gives the dehalogenated hydroxyphosphonate, and with the α,α-dichloroacetophenones which undergo monodehalogenation. Twenty three new α-hydroxyphosphonates are reported.

Convenient One Pot Synthesis of Phosphonites and H-Phosphinates

Abstract A convenient and simple one-pot method is described for the synthesis of phosphonites [RP(OEt)2, 1] and H-phosphinates [HP(O)R(OEt), 2] from triethyl phosphite and appropriate Grignard reagents.

Preparation of Esters and Amides from Carboxylic Acids by Activation with Dialkyl Phosphite-Carbon Tetrachloride Mixture

Abstract A simple one pot phase transfer catalytic method is described for the synthesis of carboxylic amides and esters from carboxylic acids and amines or alcohols, respectively. For the activation of the carboxylic acids “in situ” generated phosphoric acid diester chlorides were applied.