The synthesis of ethyl 2-[(2,2-dibenzoyl)ethenyl]amino-3-dimethyl-aminopropenoate and its application to the synthesis of fused 3-aminopyran-2-ones and 3-aminoazolo- and -azinopyrimidin-4(4H)-ones

Ethyl 2-[(2,2-dibenzoyl)ethenyl]amino-3-dimethylaminopropenoate ( 3 ) was prepared from dibenzoylmethane ( 1 ) in two steps, and used as a reagent for preparation of fused substituted 3-aminopyranones 12–15 in over 90% yield, quinolizin-4-one 16 in over 79% yield, and fused pyrimidin-4-ones 17–19 in 40–50% yield. Deprotection of (2,2-dibenzoyl)ethenyl group with either diethylamine or hydrazine hydrate produced free amino compounds 20, 21 and 22 in 35%, 91% and 71% yield, respectively.     

Synthesis and transformations of some pyrido[2,3-d]pyrimidines

A new synthetic approach for pyrido[2,3-d]pyrimidine 3-oxides and other pyrido[2,3-d]pyrimidines has been developed. This bicyclic system readily undergoes ring opening to give a variety of products, depending on the reagent and reaction conditions.

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Synthesen und Umwandlungen einiger Pyrido[2,3-d]pyrimidine

Zusammenfassung Synthesen von Pyrido[2,3-d]pyrimidin-3-oxiden und einigen anderen Pyrido[2,3-d]pyrimidinen werden beschrieben. Das bicyclische System reagiert leicht unter Ringöffnung, wobei entsprechend den Reaktionsbedingungen und Reagenzien verschiedene Produkte entstehen.

     

The effects of steric aliphatic–aliphatic interactions in the coordination polymer of bis(N,N-diethylglycinato)copper(II): Experimental evidence and theoretical modeling

New coordination polymer catena-poly[(N,N-diethylglycinato-κO,κN)copper(II)-μ-[N,N-diethylglycinato-κO¹,κN:O²]] has been obtained by single-crystal X-ray diffraction. The copper(II) was surrounded with two amino N and two carboxyl O atoms in trans position in the coordination plane. Discrete polymeric chains were produced by axial coordinative bonding between copper(II) and carbonyl oxygen atom from adjacent asymmetric unit. Molecular mechanics (MM) force field developed to study the properties of copper(II) amino acid complexes reproduced well intermolecular aliphatic–aliphatic interactions between ethyl chains and C–H?O hydrogen bonding. The relative unit cell volume reproduction was 0.3%. Theoretical conformational analysis showed that experimentally obtained conformer was not the most stable in vacuo. The calculations of the unit cell packings and intermolecular interactions for a series of conformers elucidated the reasons that governed the experimentally obtained conformer to appear in the real crystal structure. MM results suggest that intermolecular aliphatic–aliphatic interactions between ethyl groups affected a conformational change concurrent with the change in the copper(II) coordination sphere upon crystallization.     

A general synthesis of alkyl 6-substituted-pyrazolo-[3,2-c] -s-triazolo-7-carboxylates

A general synthesis of alkyl 6-methyl- and 6-phenylpyrazolo[3,2-c]-s-triazolo-7-carboxylates by photochemical Wolf rearrangement of 6-methyl- and 6-phenyl-7-diazo-8-oxo-s-triazolo-[4,3-b]pyridazine in an alcohol is described.     

Transformations of methyl 2-(2,2-disubstituted-ethenyl)amino-3-dimethylaminopropenoates. The synthesis of methyl 1-heteroaryl-1H-imidazole-4-carboxylates

Transformations of intermediates 4 , prepared from methyl 2-(2,2-disubstituted-ethenyl)amino-3-dimethylaminopropenoates 2 and sterically hindered heteroarylamines 3 , into methyl 1-heteroaryl-1H-imidazole-4-carboxylates 7 are described.     

Transformations of 1-(2-chloropyridyl-3)-4-ethoxycarbonyl-and 1-(2-chloropyridyl-3)-4-ethoxycarbonylmethyl thiosemicarbazides. Attempts to prepare pyrido[3,2-e]-1,2,4-thiadiazine

2-Chloro-3-hydrazinopyridine (2) was converted with ethoxycarbonyl and ethoxycarbonylmethyl isothiocyanates into 1,4-disubstituted thiosemicarbazides3 and4, while with phenyl isothiocyanate directly 1H-pyrido[3,2-e]-1,3,4-thiadiazine7 was formed. Attempts to cyclize the thiosemicarbazides3 and4 into pyridothiadiazine derivatives5 and6 failed. In the reaction of3 with hydrazine 2-aminothiazolo[5,4-b]pyridine (9) was formed, while4 gave only the corresponding hydrazide10. The cyclization of the side chain occurred in compound4 by heating in aqueous hydrochloric acid to give11, which was further transformed with N,N-dimethylformamide dimethyl acetal (DMFDMA) into12, while with diethyl acetylene dicarboxylate the thiazolidone derivative13 was produced.

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Transformationen von 1-(2-Chlorpyridyl-3)-4-ethoxycarbonyl- und 1-(2-Chlorpyridyl-3)-4-ethoxycarbonylmethylthiosemicarbaziden. Versuche zur Synthese von Pyrido[3,2-e]-1,2,4-thiadiazinen

Zusammenfassung 2-Chlor-3-hydrazinopyridin (2) wurde mit Ethoxycarbonyl- und Ethoxycarbonylmethylisothiocyanaten zu 1,4-disubstituierten Thiosemicarbaziden3 und4 umgesetzt, mit Phenylisothiocyanaten wurden direkt die 1H-Pyrido[3,2-e]-1,3,4-thiadiazine7 erhalten. Versuche zur Cyclisierung der Thiosemicarbazide3 und4 zu den Pyridothiadiazinderivaten5 und6 gelangen nicht. Bei der Reaktion von3 mit Hydrazin entstand 2-Aminothiazolo[5,4-b]pyridin (9),4 gab nur das entsprechende Hydrazid10. Die Cyclisierung der Seitenkette von4 gelang durch Erhitzen in wäßriger HCl unter Bildung von11, das seinerseits mit N,N-Dimethylformamiddimethylacetal (DMFDMA) weiter zu12 umgesetzt wurde, währenddessen mit Diethylacetylendicarboxylat die Thiazolidonderivate13 entstanden.

     

The structure of β-heteroaryl-α,β-dehydro-α-amino acid derivatives,intermediates in the synthesis of fused pyran-2-ones. Substituted methyl (Z)-2-benzoylamino-3-(5-oxopyrazolinyl-4)propenoates

It was shown by some chemical transformations that β-heteroaryl-α,β-dehydro-α-amino acid derivatives 3 and 7 , obtained from pyrazolone derivatives 1 or 6 and 2 , exist in Z-forms. The structure of 7 was confirmed by X-ray analysis.     

Transformation of Amino Acids into Nonracemic 1‐(Heteroaryl)ethanamines by the Enamino Ketone Methodology

N‐Protected L ‐phenylalanines 1a,b were transformed, via the corresponding Weinreb amides 2 and ethynyl ketones 3 , into chiral enamino ketones 4 (Scheme 1). Similarly, L ‐threonine 6 was transformed in four steps into the enamino ketone 10 . Cyclocondensations of 4 and 10 with pyrazolamines 11 , benzenecarboximidamide ( 12 ), and hydrazine derivatives 18 afforded N‐protected 1‐heteroaryl‐2‐phenylethanamines 15a – e, 16, 17 , and 21a – k and 1‐heteroaryl‐1‐aminopropan‐2‐ols 23a,b in good yields (Schemes 2 and 3). Finally, deprotection by catalytic hydrogenation furnished free amines 22a – g and 24a,b (Scheme 3).     

Correlations between the activities of a gamma-ray emitter calculated from different peaks in the spectrum

A model for calculating correlations between the activities of the same gamma-ray emitter calculated from different peaks in its spectrum is presented. The correlation coefficients can be expressed by the relative uncertainties of the input quantities. The use of this model in the calculation of the mean activity prevents the calculation of an excessively small uncertainty of the mean, since averaging of correlated uncertainty components is avoided.     

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 .