Naphtho[1′,2′:5,6]pyrano[2,3–6][1,5]benzodiazepine Derivatives

The reaction of 3-(dimethylamino)-1-oxo-1H-naphtho[2,1-b]pyran-2-carbaldehyde (Ia) with o-phenylenediamines or N-monosubstituted o-phenylenediamines in refluxing glacial acetic acid afforded the corresponding naphtho[1′,2′:5,6]pyrano[2,3-b][1,5]benzodiazepin-15-(8H)ones V in very good yields. A similar result was achieved when the reaction was carried out in refluxing pyridine, using N-monosubstituted o-phenylenediamine hydrochlorides. The isolation of a significant intermediate as well as the synthesis through a different univocal pathway confirmed the structure of the compounds V. Moreover the reaction of Ia with N-monosubstituted o-phenylenediamines in refluxing pyridine generally afforded only low yields of compounds V, sometimes together with naphtho[1′,2′:5,6]pyrano[2,3-b][1,5]benzodiazepin-15-(13H)ones VII, isomers of V.     

Reactions of Polycyclic Ketones with Dimethoxycarbene; a Convenient Route for a ‘One‐Pot’ Preparation of Some α‐Hydroxycarboxylic Acid Esters

Polycyclic ‘cage’ ketones, such as pentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecan‐8‐one ( 10 ), pentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecane‐8,11‐dione ( 11 ), and adamantan‐2‐one ( 16 ) were treated with the nucleophilic dimethoxycarbene (DMC; 1 ), which was generated thermally from 2,5‐dihydro‐2,2‐dimethoxy‐5,5‐dimethyl‐1,3,4‐oxadiazole ( 4a ) in boiling toluene. In this ‘one‐pot’ procedure, the α‐hydroxycarboxylic acid ester 12 or a corresponding derivative 15 or 17 was obtained (Schemes 4–7). Additionally, ‘cage’ thione 21 was treated with DMC under the same conditions yielding dimethoxythiirane 22 (Scheme 8). Subsequent hydrolysis or desulfurization (followed by hydrolysis on silica gel) of 22 gave α‐mercaptocarboxylate 25 and the corresponding desulfurized ester 24 , respectively. In all cases, the addition of DMC occurred stereoselectively, and the addition from the exo‐face is postulated to explain the structures of the isolated products.     

12H-naphtho[1′,2′:5,6]pyrano[2,3-d]pyrimidine derivatives

Reaction of 1-oxo-2-formyl-3-dimethylamino-1H-naphtho[2,1-b]pyran with amidines, guanidine, O-methylisourea, S-methylisothiourea afforded 9-substituted 12-oxo-12H-naphtho[1′,2′:5,6]pyrano[2,3-d]pyrimidines. When the reaction with O-methylisourea was carried out in anhydrous pyridine, 10,20-dioxo-10H,20H-dinaphtho[1,2-e:1′,2′-e′][1,5]diazocino[2,3-b:6,7-b′]dipyran was formed.     

1,2-fused pyrimidines. V. Synthesis of 1-alkyl or phenyl-2H-dipyrido-[1,2-a:2′,3′-d]pyrimidine-2,5(1H)-diones

The reaction of 2-[(N-acyl, N-alkyl or phenyl)amino]-4H-pyrido[1,2-a]pyrimidin-4-ones 8a-g with the N,N-dimethylformamide/phosphorus oxychloride Vilsmeier reagent 1 (95°, 90 minutes) afforded 1-alkyl or phenyl-2H-dipyrido[1,2-a:2′,3′-d]pyrimidine-2,5(1H)^?diones, 3-alkyl substituted or not, 10a-g . The starting compounds 8 were prepared by treating 2-amino-4H-pyrido[1,2-a]pyrimidin-4-ones N-alkyl substituted 7a,b or N-phenyl substituted 4 with excess anhydrides (130°, 7 hours) when the 2-(alkylamino) derivatives 7 were used in the reaction, compounds 8 were obtained along with very small amounts of 3-acyl-2-(alkylamino)-4H-pyrido[1,2-a]pyrimidin-4-ones 9 .     

Polonium 210Po activities in human blood of patients with ischaemic heart disease from Gdańsk in Poland

The determination of polonium ²¹⁰Po in human blood samples is presented and discussed in this paper. The human blood samples were collected from patients of Medical University of Gdańsk with ischaemic heart disease (morbus ischaemicus cordis, MIC). The polonium concentrations in analyzed human blood samples are very differentiated. ²¹⁰Po is of particular interest in public health and although is present in the environment in extremely low amounts, it is easily bioaccumulated to the human body. The study shows that the amount of ²¹⁰Po that is incorporated into the human body depends on the food habits and some difference in its levels could be observed between smokers and non-smokers.     

Simultaneous Anodic Stripping Voltammetric Determination of Pb and Cd,Using a Vibrating Gold Microwire Electrode,Assisted by Chemometric Techniques

Simultaneous anodic stripping voltammetric determination of Pb and Cd is restricted on gold electrodes as a result of the overlapping of these two peaks. This work describes the quantitative determination of a binary mixture system of Pb and Cd, at low concentration levels (up to 15.0 and 10.0 µg L^?1 for Pb and Cd, respectively) by differential pulse anodic stripping voltammetry (DPASV; deposition time of 30 s), using a green electrode (vibrating gold microwire electrode) without purging in a chloride medium (0.5 M NaCl) under moderate acidic conditions (HCl 1.0 mM), assisted by chemometric tools. The application of multivariate curve resolution alternating least squares (MCR‐ALS) for the resolution and quantification of both metals is shown. The optimized MCR‐ALS models showed good prediction ability with concentration prediction errors of 12.4 and 11.4 % for Pb and Cd, respectively. The quantitative results obtained by MCR‐ALS were compared to those obtained with partial least squares (PLS) and classical least squares (CLS) regression methods. For both metals, PLS and MCR‐ALS results are comparable and superior to CLS. For Cd, as a result of the peak shift problem, the application of CLS was unsuitable. MCR‐ALS provides additional advantage compared to PLS since it estimates the pure response of the analytes signal. Finally, the built up multivariate calibration models, based either in MCR‐ALS or PLS regression, allowed to quantify concentrations of Pb and Cd in surface river water samples, with satisfactory results.     

Extension and application of multivariate curve resolution-alternating least squares to four-way quadrilinear data-obtained in the investigation of pollution patterns on Yamuna River,India—A case study

This study focuses on the development and extension of Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) to the analysis of four-way datasets. The proposed extension of the MCR-ALS method with non-negativity and the newly developed quadrilinear constraints can be exploited to summarize and manage huge multidimensional datasets and resolve their four way component profiles. In this study, its application is demonstrated by analyzing a four-way data set obtained in a long term environmental monitoring study (15 sampling sites × 9 variables × 12 months × 7 years) belonging to the Yamuna River, one of the most polluted rivers of India and the largest tributary of the Ganges river. MCR-ALS resolved pollution profiles described appropriately the major observed changes on pH, organic pollution, bacteriological pollution and temperature, along with their spatial and temporal distribution patterns for the studied stretch of Yamuna River. Results obtained by MCR-ALS have also been compared with those obtained by another multi-way method, PARAFAC. The methodology used in this study is completely general and it can be applied to other multi-way datasets.     

Irradiance dependence of the He-Ne laser-induced protection against UVC radiation in E. coli strains

He-Ne laser pre-irradiation-induced protection against UVC damage was investigated in wild-type E. coli K12 strain AB1157 and its isogenic DNA repair mutant strains. At a dose of 7 kJ/m(2), pre-irradiation was observed to induce protection in recA proficient strains (AB1157 and uvrA(-) AB1886) at both the irradiances investigated (2 and 100 W/m(2)). However, at the same dose (7 kJ/m(2)), while no protection was observed at 100 W/m(2) in the recA(-) strain, some protection appeared to be there at 2 W/m(2). Mechanistic studies carried out on these strains at the two irradiances suggest that, whereas the protection observed at 100 W/m(2) is mediated by singlet oxygen, that observed at 2 W/m(2) is not. Further, the fact that protection at 100 W/m(2) was observed only in recA proficient strains suggests that it may arise due to the induction of DNA repair processes controlled by the recA gene. The latter may arise due to the oxidative stress produced by singlet oxygen generated by He-Ne laser irradiation. In contrast, the protection observed at 2 W/m(2) appears to be independent of the DNA repair proficiency of the strain.     

Carbohydrates as building blocks of privileged ligands

“Privileged ligands” are chiral auxiliaries of wide applicability in asymmetric catalysis. In the previous decades, their effective three-dimensional structures have often been reproduced by using building blocks from a “chiral pool”, such as the carbohydrates. This strategy has provided unique ligand moieties which combine the performance of “privileged ligands” with increased flexibility and accessibility. This review gives an overview of the research within this field, giving emphasis to the best results obtained with each ligand type.     

Exploiting damped techniques for nonlinear conjugate gradient methods

In this paper we propose the use of damped techniques within Nonlinear Conjugate Gradient (NCG) methods. Damped techniques were introduced by Powell and recently reproposed by Al-Baali and till now, only applied in the framework of quasi-Newton methods. We extend their use to NCG methods in large scale unconstrained optimization, aiming at possibly improving the efficiency and the robustness of the latter methods, especially when solving difficult problems. We consider both unpreconditioned and Preconditioned NCG. In the latter case, we embed damped techniques within a class of preconditioners based on quasi-Newton updates. Our purpose is to possibly provide efficient preconditioners which approximate, in some sense, the inverse of the Hessian matrix, while still preserving information provided by the secant equation or some of its modifications. The results of an extensive numerical experience highlights that the proposed approach is quite promising.