Nitrosation of methyl 2-cinnamoylamino-3-dimethylaminopropenoates. Alkyl N-cinnamoyloxalic acid hydroxyimidic amides,intermediates in the synthesis of alkyl 5-styryl-1,2,4-oxadiazole-3-carboxylates

Alkyl 2-(substituted cinnamoylamino)-3-dimethylaminopropenoates 5, prepared either from glycine ( 1 ) and substituted cinnamoyl chlorides 2 via oxazol-5(4H)-ones 4 , or from cinnamoylglycinate with t-butoxy-bisdimethylaminomethane, were transformed by nitrosation into 5-substituted-1,2,4-oxadiazole-3-carboxylates 8 . The formation of alkyl N-cinnamoyloxalic acid hydroxyimidic amides 7, which were isolated as intermediates, represent a novel synthesis of N-acyl substituted hydroxyimidic amides.     

Conformationally tailored N-[(2-methyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl)carbonyl]proline templates as molecular tools for the design of peptidomimetics. Design and synthesis of fibrinogen receptor antagonists

The proline peptide bond was shown by 2D proton NMR studies to exist exclusively in the trans conformation in benzyl (2S)-1-[[(2S)-2-methyl-6-nitro-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl]carbonyl]-2-pyrrolidinecarboxylate [(S,S)-11], benzyl (2S)-1-[[(2S)-2-methyl-7-nitro-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl]carbonyl]-2-pyrrolidinecarboxylate [(S,S)-9], and in the corresponding 6-amino and 7-amino carboxylic acids (S,S)-3 and (S,S)-4. On the other hand, the diastereomers (R,S)-11 and (R,S)-9 containing an (R)[2-methyl-6/7-nitro-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl]carbonyl moiety, and the diastereoisomers (R,S)-3 and (R,S)-4 incorporating an (R)[6/7-amino-2-methyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl]carbonyl moiety were found to exist as equilibria of trans(63-83%) and cis(17-37%) isomers. These conformationally defined templates were applied in the construction of RGD mimetics possessing antagonistic activity at the platelet fibrinogen receptor.     

Nitrosation of methyl 2-acylamino-3-dimethylaminopropenoates. A simple conversion of n-acylglycines into 5-substituted 1,2,4-Oxadiazole-3-carboxylates

A novel simple synthesis of 5-substituted-1,2,4-oxadiazole-3-carboxylates 5 from N-acylglycines 1 , which are transformed with DMF in the presence of phosphorus oxychloride into 2-substituted-4-dimethyl-aminomethyleneoxazol-5(4H)-ones 2 , followed by opening into 2-aroylamino-3-dimethylamino-propenoates 3 , and nitrosation to give the oximes 4 as intermediates, which cyclize spontaneously into 5-substituted-1,2,4-oxadiazole-3-carboxylates 5 . The compounds 2 can be transformed into 5 without isolation of 3 and 4 .     

Synthese von Tetracyanoniccolat-clathraten mit Benzol Kurze Mitteilung

Zusammenfassung Durch Ersetzung des Cadmiums im Clathrat Cden[Ni(CN)₄]·2C₆H₆ wurden drei Verbindungen des TypsM(en) _m[Ni(CN)₄]·nC₆H₆ (M ²⁺=Ni, Cu, Zn;m=2–3;n=0.14–0.28) hergestellt und charakterisiert.

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Synthesis of ethylendiamine-(metal II)-tetracyanoniccolate dibenzene clathrate compounds

Replacing cadmium ion in Cden[Ni(CN)₄]·2C₆H₆ clathrate compound three compounds ofM(en) _m[Ni(CN)₄]·nC₆H₆ type (M ²⁺=Ni, Cu, Zn;m=2–3;n=0.14–0.28) were prepared and characterized.

     

Quasicontinuous functions,minimal usco maps and topology of pointwise convergence

In [HOLá, Ľ.—HOLY, D.: Pointwise convergence of quasicontinuous mappings and Baire spaces, Rocky Mountain J. Math.] a complete answer is given, for a Baire space X, to the question of when the pointwise limit of a sequence of real-valued quasicontinuous functions defined on X is quasicontinuous. In [HOLá, Ľ.—HOLY, D.: Minimal USCO maps, densely continuous forms and upper semicontinuous functions, Rocky Mountain J. Math. 39 (2009), 545–562], a characterization of minimal USCO maps by quasicontinuous and subcontinuous selections is proved. Continuing these results, we study closed and compact subsets of the space of quasicontinuous functions and minimal USCO maps equipped with the topology of pointwise convergence. We also study conditions under which the closure of the graph of a set-valued mapping which is the pointwise limit of a net of set-valued mappings, is a minimal USCO map.     

Concise synthesis of 22-hydroxyacuminatine, cytotoxic camptothecinoid from Camptotheca acuminata, by pyridone benzannulation

A short, efficient synthesis of 22-hydroxyacuminatine, starting from a readily accessible hydroxy pyridone, is presented; key steps include a Heck coupling with methyl pentadienoate, a flash vacuum pyrolytic cyclization, and a Friedl?nder condensation.     

Derivations mapping into the socle, II

Let be a unital Banach algebra. Several characterizations of continuous derivations of having only elements with finite spectrum in their ranges are obtained. In particular, if is semisimple, then such derivations map into its socle.

     

Answer to “information flow,causality, and the classical theory of Tachyons”

We briefly answer the comments in Information Flow, Causality and the Classical Theory of Tachyons by Basano.Work partially supported by MPI (ex-art. 286 T.U.).     

New agitated and thermostatized cell for in situ monitoring of fast reactions by synchrotron SAXS

A thermostatized and agitated sample cell for synchrotron small‐angle X‐ray scattering (SAXS) measurements of liquid samples (homogeneous or heterogeneous) has been developed. The cell is composed of a compact main body with inlet and outlet windows for the beams of light. The volume of the cell is approximately 0.8 ml and the distance between the windows is 5 mm to allow accurate SAXS measurements. The cell is thermostatized by means of a jacket that surrounds the sample holder and it is connected to a thermostatic bath. In addition, the cell has a top and a bottom lid that allow easy cleaning and maintenance without demounting the optical windows. The cell has been used to run SAXS measurements of liquid samples and, for the first time, a mini‐emulsion polymerization reaction has been monitored by SAXS.     

Mechanistic models for pool nucleate boiling heat transfer: input and validation

Correlations for nucleate boiling heat transfer should be improved, or in the long term possibly be replaced, by the development of mechanistic simulations that include the non-uniform spacing and variable characteristics of the nucleation sites and non-linear interactions between the sites. This paper discusses the interactions that should be included in simulations and some lessons from a first attempt to validate a particular simulation against experimental spatio-temporal data for wall temperature. Input data for nucleation site positions and characteristics are a particular problem and the prospects for obtaining this data from measurements that are independent of boiling are discussed.