Rearrangements of 5-acetyl-3-benzoylamino-6-(2-dimethylamino-1-ethenyl)-2H-pyran-2-one and 3-benzoylamino-6-(2-dimethylamino-1-ethenyl)-5-ethoxycarbonyl-2H-pyran-2-one into 1-aminopyridine,pyrano[2,3-b]pyridine and isoxazole derivatives

Rearrangements of 5-acetyl-3-benzoylamino-6-(2-dimethylamino-1-ethenyl)-2H-pyran-2-one ( 1 ) and 3-benzoylamino-6-(2-dimethylamino-1-ethenyl)-5-ethoxycarbonyl-2H-pyran-2-one ( 7 ) in the presence of N-nucleophiles, such as ammonia, hydrazine, and hydroxylamine, into 1-aminopyridine, pyrano[2,3-b]-pyridine, and isoxazole derivatives 5, 11 , and 15 is described. In the reaction of compounds 1 and 7 with C-nucleophiles, such as 5,5-dimethyl-1,3-cyclohexanedione and barbituric acid, only substitution of the dimethylamino group is taking place to give the compounds 17, 18 , and 20 .     

The synthesis and transformations of ethyl (Z)-2-[2,2-bis(ethoxycarbonyl)vinyl]amino-3-dimethylaminopropenoate,a new reagent in the synthesis of heterocyclic compounds

Ethyl (Z)-2-[2,2-bis(ethoxycarbonyl)vinyl]amino-3-dimethylaminopropenoate (5) , a new reagent in the synthesis of heteroaryl substituted β-amino- α,β- -dehydro—amino acid derivatives and some fused hetero-cyclic systems, was prepared from ethyl N-2,2-bis(ethoxycarbonyl)vinylglycinate (3) and N,N-dimethyl-formamide dimethyl acetal (4) . The substitution of the dimethylamino group in the compound 5 with heterocyclic amines produced ethyl 2-[2,2-bis(ethoxycarbonyl)vinyl]amino-3-heteroarylaminopropenoates 7a-f and, in some instances, [2,2-bis-(ethoxycarbonyl)vinyl]aminoazolo- or -azinopyrimidine derivatives 8g-k.     

Transformations of 1-azinyl-4-ethoxycarbonyl thiosemicarbazides. The synthesis of 3-ethoxycarbonylamino-s-triazolo[4,3-x]azines

1-Azinyl-4-ethoxycarbonyl thiosemicarbazides4,5, and12 and 1-azinyl-4-ethoxycarbonylmethyl thiosemicarbazide17, prepared from the corresponding heterocyclic hydrazino compounds and ethoxycarbonyl isothiocyanate or ethoxycarbonylmethyl isothiocyanate, were converted by oxidation with bromine in acetic acid into derivatives of fused 3-ethoxycarbonylamino-s-triazolo[4,3-a]pyridine6, -pyridazine7, and -pyrazine13,18 and20. The thiosemicarbazide derivative8 was transformed at 0 °C into bis-s-triazolo[4,3-b:34-f]pyridazine derivative9, while at room temperature 6-bromo-s-triazolo[4,3-b]pyridazine (10) was obtained. Further transformations of 8-substituted 3-ethoxycarbonylamino-s-triazolo[4,3-a]pyrazines13 and14 afforded derivatives of bis-s-triazolo[4,3-a:3,4-c]pyrazine15 and s-triazolo[4,3-a]tetrazolo[1,5-c]pyrazine16.

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Transformation von 1-Azinyl-4-ethoxycarbonylthiosemicarbaziden. Die Synthese von 3-Ethoxycarbonylamino-s-triazolo[4,3-x]azinen

Zusammenfassung Die aus den entsprechenden heterocyclischen Hydrazinverbindungen und Ethoxycarbonylmethylisothiocyanaten hergestellten 1-Azinyl-4-ethoxycarbonylthiosemicarbazide4,5 und12 und 1-Azinyl-4-ethoxycarbonyl-methylthiosemicarbazid17 wurden mittels Oxidation mit Brom in Essigsäure in die kondensierten Produkte 3-Ethoxycarbonylamino-s-triazolo[4,3-a]pyridin6, -pyridazin7 und -pyrazine13,18 und20 übergeführt. Das Thiosemicarbazidderivat8 wurde bei 0 °C in das Bis-s-trazolo[4,3-b:3,4-f]pyridazin-Derivat9 transformiert, währenddessen bei Raumtemperatur 6-Brom-s-triazolo[4,3-b]pyridazin (10) erhalten wurde. Weitere Transformationen der 8-substituierten 3-Ethoxycarbonylamino-s-triazolo[4,3-a]pyrazine13 und14 ergaben Derivate von Bis-s-triazolo[4,3-a:3,4-c]pyrazin15 und s-Triazolo[4,3-a]tetrazolo[1,5-c]pyrazin (16).

     

Trace analysis of anionic surfactants in mineral waters and soft drinks by spectrophotometry

The applicability of the extractive spectrophotometric method using Ethyl Violet as the chromogenic reagent for identification and quantification of anionic surfactants in different types of mineralized drinking waters, as well as in some non-alcoholic beverages, was investigated. The matrix-analyte interactions of major water constituents and soft-drink ingredients in the combinations and concentration ranges met in practice were studied individually. The method was evaluated by performing recovery tests on commercial and natural samples, with sodium dodecyl sulphate added as a model surfactant. The recoveries at the 57.6 and 86.4 g/l levels ranged from 98% to 104%.     

Conformational enantiomeric disorder in tripivaloylmethane

Tripivaloylmethane [systematic name: 4‐(2,2‐dimethylpropanoyl)‐2,2,6,6‐tetramethylheptane‐3,5‐dione], C₁₆H₂₈O₃, is a 1,3,3′‐triketone with C₃ molecular symmetry, prepared by α‐acylation of 2,2,6,6‐tetramethylheptane‐3,5‐dione with 2,2‐dimethylpropanoyl anhydride in the presence of barium metal. The molecules are conformationally chiral and pack so that each molecular site is occupied with equal probability by the two enantiomers. The carbonyl groups of the two superimposed enantiomeric molecules are at an angle of 75.4 (16)°.     

Density functional theory investigation of physical properties of the OCCN radical and the cation

Structural and thermodynamic properties for the OCCN radical and its cation were estimated with hybrid, gradient-corrected and local density functional theory methods by using three various Gaussian type basis sets. It was estimated that the radical structure should be a zig-zag structure, which corresponds to the sp² hybridization of the carbonyl carbon, while the OCCN cation is linear. The radical ionization potential should be between 8.7 and 9.1 eV with the enthalpy of formation at approximately 51 kcal/mol. It was computed in the infrared spectra that there were two strong absorptions at 1863 and 2080 cm⁻¹ for the CO and the CN functionalities and they should be observable for the OCCN radical.     

Least committed basic belief density induced by a multivariate Gaussian: Formulation with applications

We consider here the case where our knowledge is partial and based on a betting density function which is n-dimensional Gaussian. The explicit formulation of the least committed basic belief density (bbd) of the multivariate Gaussian pdf is provided in the transferable belief model (TBM) framework. Beliefs are then assigned to hyperspheres and the bbd follows a χ² distribution. Two applications are also presented. The first one deals with model based classification in the joint speed–acceleration feature space. The second is devoted to joint target tracking and classification: the tracking part is performed using a Rao–Blackwellized particle filter, while the classification is carried out within the developed TBM scheme.     

Application of FT-based MMSE deconvolution method for cerebral blood flow measurement in patients with leukoaraiosis

Introduction

The bolus-tracking (BT) technique is the most popular perfusion-weighted (PW) dynamic susceptibility contrast MRI method used for estimating cerebral blood flow (CBF), cerebral blood volume and mean transit time. The BT technique uses a convolution model that establishes the input–output relationship between blood flow and the vascular tracer concentration. Singular value decomposition (SVD)- and Fourier transform (FT)-based deconvolution methods are popular and widely used for estimating PW MRI parameters. However, from the published literature, it appears that SVD is more widely accepted than other methods. In a previous article, an FT-based minimum mean-squared error (MMSE) technique was proposed and simulation experiments were performed to compare it with the well-established circular SVD (oSVD) method. In this study, the FT-based MMSE method has been used to estimate relative CBF (rCBF) in 13 patients with white matter lesions (WMLs) (leukoaraiosis), and results are compared with the widely used oSVD method.

Materials and Methods

Thirteen patients with leukoaraiosis were imaged on a 1.5-T Siemens whole-body scanner. After acquiring the localizer and structural scans consisting of FLAIR (fluid attenuated with inversion recovery), T₁-weighted and T₂-weighted images, perfusion study was implemented as part of the MRI protocol. For each patient and method, two values were calculated: (a) rCBF for normal white matter (NWM) ROI, obtained by dividing the average CBF value in NWM ROI with average CBF in gray matter (GM) ROI, and (b) rCBF for WML ROI, obtained by dividing the average CBF value in WML ROI with average CBF in GM ROI. Results for the two deconvolution methods were computed.

Results and Discussion

A significant (P<.05) decrease in estimated rCBF was observed in the WML in all the patients using the MMSE method, while for the oSVD method, the decrease was observed in all but one patient. Initial results suggest that the MMSE method is comparable to the oSVD method for estimating rCBF in NMW while it may be better than oSVD for estimating rCBF in lesions of low flow. Studies involving a larger patient population may be required to further validate the findings of this work.     

Reactions of alkyl (z)‐2‐[(E)‐2‐ethoxycarbonyl‐2‐(2‐pyridinyl)‐ethenyl]amino‐3‐dimethylaminopropenoates with C‐ and N‐nucleophiles. the synthesis of fused pyranones,pyridinones and pyrimidinones

Alkyl 2‐[2‐ethoxycarbonyl‐2‐(2‐pyridinyl)ethenyl]amino‐3‐dimethylaminopropenoates 3 and 4 were transformed with C‐and N‐nucleophiles into β‐heteroaryl‐α,β‐didehydro‐α‐amino acid derivatives 13 ‐ 16 , substituted 3‐amino‐4H‐quinolizin‐4‐one 17, 2H,5H‐benzo[b]pyran‐2,5‐dione 18 and 19 , 2H,5H‐pyrano[4,3‐b]pyran‐2,5‐dione 20 , 2H,5H‐pyrano[3,2‐c]benzo[b]pyran‐2,5‐dione 21 , 2H‐1‐benzopyran‐2‐one 22 and 24 , pyrido[l,2‐a]pyrimidin‐4‐one 31–34 and 39 derivatives, and N‐heteroaryl‐1H‐imidazole‐4‐carboxylates 37 and 38 .