Search

Mono- and disubstituted 4-CF 3 β-lactams at the C-3 position have been obtained stereoselectively under basic conditions. A wide range of function such as alcohols, alkyls, aryls, esters, and double and triple bonds have been introduced.

A study on the α-(difluoromethyl)styrene (DFMST) reactivity under conventional radical copolymerization conditions is presented. Although the homopolymerization of DFMST failed, its radical bulk copolymerization with styrene (ST) led to the synthesis of fluorinated aromatic polymers (FAPs). The resulting novel poly(DFMST- co -ST) copolymers were characterized by 1 H, 19 F and 13 C NMR spectroscopies that evidenced the successful incorporation of DFMST units into copolymers and enabled the assessment of their respective molar percentages (10.4-48.2 mol%). The molar masses were in the range of 1900-17 200 g mol -1 . The bulkier CF 2 H group in the α-position induced the lower reactivity of the DFMST comonomer. ST and DFMST monomer reactivity ratios ( r DFMST = 0.0 and r ST = 0.70 ± 0.05 at 70 °C) were determined based on linear least-square methods. These values indicate that DFMST monomer is less reactive than ST, retards the polymerization rate, and thus reduces the molar masses. Moreover, the thermal properties ( T g -ST) copolymer (10.4/89.6) was assessed by simultaneous thermal analysis coupled with Fourier-transform infrared spectroscopy and thermogravimetric analysis coupled with mass spectrometry showing that H T d ) of the resulting copolymers indicate that the presence of DFMST units incorporated into poly(ST) structure promotes an increase of the T H group at the α-position of styrene comonomers on surface free energy of the copolymer films. Water and diiodomethane contact angle (CA) measurements confirmed that these copolymers ( g values up to 109 °C and a slightly better thermal stability than that of poly(ST). Additionally, the thermal decomposition of poly(DFMST- co -ST) copolymer (10.4/89.6) was assessed by simultaneous thermal analysis coupled with Fourier-transform infrared spectroscopy and thermogravimetric analysis coupled with mass spectrometry showing that H 2 O, CO 2 , CO and styrene were released. The surface analysis was focused on the effects of the -CF 2 H group at the α-position of styrene comonomers on surface free energy of the copolymer films. Water and diiodomethane contact angle (CA) measurements confirmed that these copolymers ( M n = 2300-17 200 g mol -1 ) are not exactly the same as polystyrenes ( M n = 2100-21 600 g mol -1 ) in the solid state. The CA hysteresis for poly(ST) (6-8°) and poly(DFMST- co -ST) copolymers (3-5°) reflected these differences even more accurately., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Transformations of α-hydroxyphosphonates derived from proline or serine by treatment with different deoxyfluorinating reagents (DAST, Deoxofluor, PyFluor) are reported. Depending on the applied reagent, as well as the protecting group used ( N -Cbz, N -Boc, N -Bn) different types of products are observed. The reaction of N -Cbz or N -Boc prolinols with DAST or Deoxofluor due to aziridinium intermediate participation gave fluorinated amino phosphonates such as piperidine and pyrrolidine derivatives and/or oxazolidine-2-ones. Similarly, the analogous reaction of N -Cbz or N -Boc protected serinol yielded oxazolidine-2-ones or its fluorinated analogues. As the second type of product formed by DAST-induced reaction of serine derivatives, aziridines were obtained. Only in the case of deoxyfluorination of N -benzyl prolinols were both diastereoisomers of β-fluoropiperidine-α-phosphonates formed, while the reaction of protected N -benzyl serinols gave fluorinated oxazolidines. Moreover, application of PyFluor gave sulfonate derivatives., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Direct conversion of the α-hydroxyl group by para -toluenesulfonamide to yield α-( N -tosyl)aminophosphonates is reported. α-Aminophosphonates 23a,b-37a,b were obtained from the corresponding α-hydroxyphosphonates 6a,b-21a,b in the presence of K 2 CO 3 , via the retro-Abramov reaction of the appropriate aldehydes, 1-5. The subsequent formation of imines with simultaneous addition of diethyl phosphite provided access to the α-sulfonamide phosphonates 23a,b-37a,b with better diastereoselectivity than in the case of the Pudovik reaction. The mechanism for this transformation is proposed herein. When Cbz N -protected aziridine 9a,b and phenylalanine analogue 12a,b were exploited, intramolecular substitution was observed, leading to the corresponding epoxide 38 as the sole product, or oxazolidin-2-one 39 as a minor product. Analogous substitution was not observed in the case of proline 18a,b and serine 21a,b derivatives., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The application of ab initio and DFT computational methods at six different levels of theory (MP2/cc-pVDZ, MP2/aug-cc-pVTZ, B3LYP/cc-pVDZ, B3LYP/aug-cc-pVTZ, M06/cc-pVDZ, and M06/aug-cc-pVTZ) to meta- and para-substituted fluoro- and trifluoromethylbenzene derivatives and to 1-fluoro- and 1-trifluoromethyl-2-substituted trans-ethenes allowed the study of changes in the electronic and geometric properties of F- and CF3-substituted systems under the impact of other substituents (BeH, BF2, BH2, Br, CFO, CHO, Cl, CN, F, Li, NH2, NMe2, NO, NO2, OH, H, CF3, and CH3). Various parameters of these systems have been investigated, including homodesmotic reactions in terms of the substituent effect stabilization energy (SESE), the π and σ electron donor-acceptor indexes (pEDA and sEDA, respectively), the charge on the substituent active region (cSAR, known earlier as qSAR), and bond lengths, which have been regressed against Hammett constants, resulting mostly in an accurate correspondence except in the case of p-fluorobenzene derivatives. Moreover, changes in the characteristics of the ability of the substituent to attract or donate electrons under the impact of the kind of moiety to which the substituent is attached have been considered as the indirect substituent effect and investigated by means of the cSAR model. Regressions of cSAR(X) versus cSAR(Y) for any systems X and Y allow final results to be obtained on the same scale of magnitude.

Chemical biology is a new branch of science characteristic with global description of biological processes occurring within the cell. It covers synthesis of new chemical compounds for systems biology studies and search for natural small molecular weight chemical compounds with high cellular regulatory potential. Chemical biology power is based on 3 pillars as chemical synthesis, computer calculations and systems biology.

Various pentafluoropropenyl derivatives of pyrimidine and purine bases have been obtained in good to high yield. The procedure involves the reaction of appropriate lithium derivatives prepared from both electron-rich and electron-poor pyrimidines, with the hexafluoropropene at a low temperature, via an addition-elimination process. Organolithiums of pyrimidine and purine bases give addition-elimination products as E/Z mixtures, whereas the products of the reaction of lithium amide of protected inosine with hexafluoropropene contain traces of an addition product as well as the stable perfluoroenamine. The methodology proposed allows a series of perfluorovinyl nucleobases to be obtained quickly and conveniently.

One possible mechanism of lowering of the birth weight by tobacco smoke is disturbance in zinc transfer trough placenta caused by accumulation of cadmium in placenta. The aim of the study was determination of cadmium and zinc in placenta of smoking women and correlation its with cotinine concentration and birth weight The study shown that concentration of cotinine in urine of smoking woman was 859+/-1234 ng/mg creatinine. Cadmium and zinc concentrations in smokers were higher (Cd 0.095+/-0.041 microg/g; Zn 46.7+/-8.3307 microg! g) than in non smokers (Cd 0.067 +/-0.022 microg/g; Zn 41.0+/-5.54 microg/g). Concentration of cadmium in placenta shown week correlation with concentration of cotinine in urine. The birth weight of newborn of smoking women (2935.7+/-836.83 g) was statistically lower than non smokers (3288.9 +/-744.47 g), however it was not correlated with placenta cadmium and zinc concentration. The high variability of the ratio of zinc to cadmium concentration caused that was not statistical differences between studied groups. The performed research shown the influence of cigarette smoking of birth weight and cadmium concentration in placenta, however did not proved the hypotheses that accumulation of cadmium and zinc in placenta influence on birth weight.

Tobacco smoke contain few thousands of chemical compounds, among them heavy metals. From toxicological point of view most important are lead, cadmium and radioactive polonium 210. The aim of the study was determination of cadmium in urine of tobacco smoking pregnant woman and checking if there is a correlation between the concentration of cadmium and cotinine, the most frequently used tobacco smoke biomarker. The study showed that concentration of cotinine in urine of smoking women was 702.5 +/- 1131.4 ng/mg creatinine and ranged from 50 to more than 6000 ng/mg creatinine. Cadmium concentration in smokers was 1.6 +/- 2.6 ng/ml and ranged from 0 to 11.5 ng/ml. In urine of woman who do not smoke and are not exposure to ETS was 1.1 +/- 2.2 ng/ml in the range 0-2.5 ng/ml and was not statistically different from concentration of cadmium in urine of smoking pregnant woman. In any one non-smoking woman, concentration of cadmium was not higher than 5 ng/ml, but in 11.8% of smoking women this level was exceeded. Calculations showed a weak correlation between concentration of cadmium and cotinine in urine of smoking pregnant women.

The structure of internal [2+2] photodimers of 1,1'-trimethylene-bis-(5-fluoro) uracil derivatives has been studied. All investigated compounds have cis-syn geometry with puckered endocyclic cyclobutane ring and chair-like conformation of 1,3-diazacycloheptane ring.