A facile two synthon approach to the camptothecin skeleton

A synthesis of deethyldesoxycamptothecin via the reaction of two readily accessible synthons is described. One of the synthons constitutes the ABC ring system of camptothecin, while the second provides all the C atoms of the rings D and E. The synthetic approach is suited for the total synthesis of camptothecin analogues.     

Evaluation of new pregnane derivatives as 5alpha-reductase inhibitor

The objective of this study was to synthesize several new pregnane derivatives and evaluate them as antiandrogens. From the commercially available 16-dehydropregnenolone acetate (7), two new steroidal compounds were synthesized: 17alpha-hydroxy-17beta-methyl-16beta-phenyl-D-homoandrosta-1,4,6-triene-3,20-dione (18) and 17alpha-acetoxy-17beta-methyl-16beta-phenyl-D-homoandrosta-1,4,6-triene-3,20-dione (19). The 5alpha-reductase inhibitory effect of the new compounds 18 and 19 together with the previously synthesized intermediates 7, 8, 13, 16, and 17 was determined in three different models: gonadectomized hamster flank organs diameter size, incorporation of [1,2-(14)C]sodium acetate into lipids in flank organs and conversion of [3H]testosterone (T) to [3H]dihydrotestosterone (DHT) by Penicillium crustosum. The evaluation of these steroids was carried out with three different controls: one group was treated with vehicle, the second with T and the third group with T plus finasteride. The pharmacological results from this work demonstrated that T significantly increases the diameter of the pigmented spot on the flank organs (p<0.05) as well as the incorporation of labeled sodium acetate into lipids in gonadectomized hamster flank organs (from 0.125 to 0.255 nmol per gland). In this study we also observed that broth of Penicillium crustosum converted [3H]T to [3H]DHT in a manner comparable to that of the flank organs. All experiments indicated that finasteride as well as steroids 7, 8, 13, 16-19 reduced significantly the conversion of T to DHT in P. crustosum. These compounds also decrease the size of the pigmented spot in the flank organs as well as reducing the incorporation of radiolabeled sodium acetate into lipids; T and the control sample (treated with vehicle only) were used for comparison. Apparently the presence of the 4,6-diene-3,20-dione moiety and also the C-17 ester group produce a higher inhibitory effect on the parameters used. PPThe data from this study indicated also that the three models used for the pharmacological evaluation exhibited comparable results.     

Vibrational study of the metal-adsorbate interaction of phenylacetic acid and alpha-phenylglycine on silver surfaces

Raman and SERS spectra of phenylacetic acid and alpha-phenylglycine on silver sols have been recorded at several concentrations and pH values. The alpha-phenylglycine has been also studied in D(2)O. The respective vibrational assignments have been proposed and the analysis of the SERS spectra has made it possible to conclude that phenylacetic acid links to the metal through its carboxylate group only, while alpha-phenylglycine links also through its amino group. In both cases the aromatic ring seems to be almost perpendicular to the metal surface. On the other hand, the contribution of the charge transfer (CT) mechanism to the enhancement of the SERS spectra has been calculated as well and it is found to be very important in both molecules. The band most enhanced by this mechanism is that of vibration 8a, mainly in alpha-phenylglycine.     

A simple and versatile method for the synthesis of acetals from aldehydes and ketones using bismuth triflate

Acetals are obtained in good yields by treatment of aldehydes and ketones with trialkyl orthoformate and the corresponding alcohol in the presence of 0.1 mol % Bi(OTf)3.4H2O. A simple procedure for the formation of acetals of diaryl ketones has also been developed. The conversion of carbonyl compounds to the corresponding 1,3-dioxolane using ethylene glycol is also catalyzed by Bi(OTf)3.4H2O (1 mol %). Two methods, both of which avoid the use of benzene, have been developed.     

Simple and rapid determination of the drug naproxen in pharmaceutical preparations by heavy atom-induced room temperature phosphorescence

A simple, selective and sensitive heavy atom-induced room temperature phosphorimetric method (HAI-RTP) is described for the determination of naproxen (NAP) in pharmaceutical preparations. The phosphorescence signals are a consequence of intermolecular protection when analytes are, exclusively, in presence of a heavy atom salt and sodium sulfite as an oxygen scavenger to minimize RTP quenching. These variables selection constitute the basis of a HAI-RTP method for the determination of naproxen (detection limit 17.6 ng ml(-1); 1.71% relative standard deviation at 250 ng ml(-1)). The method has been applied satisfactorily to the analysis of pharmaceutical preparations.     

Water absorption of a diglycidyl ether of bisphenol A/1,3-bisaminomethylcyclohexane (DGEBA/1,3-BAC) epoxy resin system

The diffusive and dynamic mechanical behavior of the DGEBA/1,3-BAC epoxy resin system was studied during water absorption. The diffusion of water was investigated at 100% relative humidity, by immersion of specimens in water at 60, 80 and 100°C. In all absorption experiments, water diffusion followed Fick's law. Diffusion coefficients and saturated water concentrations are given for these temperatures. The activation energy for diffusion was determined from the relationship between the diffusion coefficient and the reciprocal of the absolute temperature. The value obtained was 31.2 kJ mol^–1. Dynamic mechanical analysis of samples immersed in 100°C water and with various water contents showed both a shift of T_g, defined by thetan peak, to lower temperatures and a slight decrease in the dynamic modulus in the presence of water. These effects are probably a result of plasticization.This work was supported by the Xunta de Galicia through grant XUGA-17201A92.     

Elliptic Reconstruction and a Posteriori Error Estimates for Fully Discrete Semilinear Parabolic Optimal Control Problems

This article studies a posteriori error analysis of fully discrete finite element approximations for semilinear parabolic optimal control problems. Based on elliptic reconstruction approach introduced earlier by Makridakis and Nochetto [25], a residual based a posteriori error estimators for the state, co-state and control variables are derived. The space discretization of the state and co-state variables is done by using the piecewise linear and continuous finite elements, whereas the piecewise constant functions are employed for the control variable. The temporal discretization is based on the backward Euler method. We derive a posteriori error estimates for the state, co-state and control variables in the $L^\infty(0,T;L^2(\Omega))$-norm. Finally, a numerical experiment is performed to illustrate the performance of the derived estimators.     

The crystal structure of eudesma-4(15),7(11)-dien-8α, 12-olide: a sesquiterpene lactone fromTrattinickia rhoifolia Willd

The title compound, formula C₁₅H₂₀O₂, is orthorhombic, P2₁2₁2₁ witha=8.747(2),b=12.025(3),c=12.554(3)Å,Z=4, andD _m =1.32(2)g/ml. The structural analysis shows that the compound corresponds to eudesma-4(15),7(11)-dien-8,12-olide, a sesquiterpene lactone previously isolated fromAster umbellatus but whose crystal structure was unknown.     

Lines of curvature near umbilical points on surfaces immersed in R4

LetM be a compact orientable surface,I:M R⁴ an immersion of classC ^r and a normal unitary smooth vector field. We prove that in the space of pairs (I, ) the family of pairs all whose umbilical points are Darbouxian is generic.