Zsuzsa M. Jászay

Study of the diastereoisomers formed between (N-alkyl)-pipecolic acid-anilides and 2R,3R-tartaric acid or O,O′-dibenzoyl-2R,3R-tartaric acid. Do the tartaric acids form molecular-complexes, instead of salts during optical resolutions?

It was found that during the optical resolution of (N-alkyl)-pipecolic acid-anilides by 2R,3R- tartaric acid and O,O′-dibenzoyl-2R,3R-tartaric acid that the precipitated diastereoisomer was not the salt but a diastereoisomeric complex in 8 cases from 13. The results indicate that tartaric acids may be used as general resolving agents for optical resolution of racemates even having no basic group.

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.

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.

The Preparation and Properties of Some α-Acyloxy- and α-Carbamoyloxy-Phosphonothionates

New f -acyloxy and f -carbamoyloxy derivatives of dimethyl 2,2,2-trichloroethyl-phosphonothionate have been prepared, characterized, and screened for activity against free-living soil nematodes. Several of the more easily hydrolysable esters, and also the N -methylcarbamoyl derivative, were as active as the parent pesticide, dimethyl f -hydroxy-2,2,2-trichloroethylphosphonothionate, after an induction period during which the active species is assumed to be released in vivo . It is concluded that the 2,2,2-trichloroethyl group is essential for activity in compounds of these types and that the presence of the N -methylcarbamoyl group does not in itself confer activity.

EFFICIENT SOLID/LIQUID PHASE-TRANSFER CATALYTIC DIAZO TRANSFER SYNTHESIS

A simple and efficient solid/liquid phase-transfer catalytic diazo transfer reaction for the synthesis of diazocarbonyl, diazophosphonyl, and diazophosphinyl compounds is reported.

Enantioselective Synthesis of α-Alkoxy-Phosphonates by Chiral Phase Transfer Catalysis

Abstract Enantioselective PTC phosphorylation of aldehydes performed in a two phase (aq. NaOH/toluene) system mediated by chiral crown ether incorporating one or two sugar units. To avoid the rearrangement of hydroxy phosphonate 3 to nonchiral mixed phosphate ester 4 the hydroxy phosphonate was trapped by alkylation to give 5.