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Molecules, Volume 8, Issue 5 (May 2003), Pages 401-458

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Research

Open AccessArticle Dipolar Cycloaddition Reactions with Quinazolinones: A New Route for the Synthesis of Several Annelated Pyrrolo- and Pyridazinoquinazoline Derivatives
Molecules 2003, 8(5), 401-410; doi:10.3390/80500401
Received: 26 November 2002 / Revised: 6 April 2003 / Accepted: 9 April 2003 / Published: 31 May 2003
Cited by 5 | PDF Full-text (291 KB) | HTML Full-text | XML Full-text
Abstract
The novel 2-aryl-3a,4,12,12a-tetrahydropyrrolo[3',4':4,3]-pyridazino[6,1-b]-quinazoline-1,3,6-triones (6a–d), 2-aryl-10-oxopyridazino[6,1-b]-quinazoline-3-thio-carboxamides (10a–d) and 2-aryl-3-nitro-1,2,3,4-tetrahydro-pyridazino[6,1-b]quinazolin-10-ones (12a–d) were synthesized via a new, facile one step route involving the reactions of the zwitterion 4, formed in situ, with a variety of N-arylmaleimides 5, 3-aryl-2-cyano-thioacrylamides 8 and ω-nitrostyrenes 11. Dehydrogenation of
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The novel 2-aryl-3a,4,12,12a-tetrahydropyrrolo[3',4':4,3]-pyridazino[6,1-b]-quinazoline-1,3,6-triones (6a–d), 2-aryl-10-oxopyridazino[6,1-b]-quinazoline-3-thio-carboxamides (10a–d) and 2-aryl-3-nitro-1,2,3,4-tetrahydro-pyridazino[6,1-b]quinazolin-10-ones (12a–d) were synthesized via a new, facile one step route involving the reactions of the zwitterion 4, formed in situ, with a variety of N-arylmaleimides 5, 3-aryl-2-cyano-thioacrylamides 8 and ω-nitrostyrenes 11. Dehydrogenation of the tetrahydro derivatives 6a–d and 12a–d in nitrobenzene resulted in the formation of 2-arylpyrrolo[3',4':4,3]-pyridazino[6,1-b]quinazoline-1,3,6-triones (7a–d) and 2-aryl-3-nitropyridazino[6,1-b]quinazolin-10-ones (13a–d), respectively. The structures of the products were confirmed by elemental analysis and spectral data. Full article
Open AccessArticle Synthesis and Structure of bis(Dibutyldithiocarbamate)zinc(II): Zn2[(n-Bu)2NCSS]4
Molecules 2003, 8(5), 411-417; doi:10.3390/80500411
Received: 9 February 2003 / Revised: 3 April 2003 / Accepted: 6 April 2003 / Published: 31 May 2003
Cited by 9 | PDF Full-text (333 KB) | HTML Full-text | XML Full-text
Abstract
The binuclear zinc (II) complex Zn2[(n-Bu)2NCSS]4 has been prepared, and its crystal and molecular structure have been determined by x-ray diffraction. The crystal is monoclinic, space group C2/c, with a=23.329(3)Å, b=17.090(2)Å, c=16.115(2)Å, α =90°, β=127.560(10)°, γ=90°, z=4, V=5039.1(11)Å3, F(000)=2016, R=0.0450, and
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The binuclear zinc (II) complex Zn2[(n-Bu)2NCSS]4 has been prepared, and its crystal and molecular structure have been determined by x-ray diffraction. The crystal is monoclinic, space group C2/c, with a=23.329(3)Å, b=17.090(2)Å, c=16.115(2)Å, α =90°, β=127.560(10)°, γ=90°, z=4, V=5039.1(11)Å3, F(000)=2016, R=0.0450, and Rw=0.1192. The crystal structure shows that two S-N-S atom chains, belonging to the different dibutyldithiocarbamate ligands, bridge two zinc (II) ions. Each zinc (II) ion coordinates to four S atoms. The coordination geometry around the zinc (II) is a tetrahedron, however, the coordination sphere of two zinc ions in the dimer is best described as a distorted octagon. The X-ray photoelectron spectra, IR and UV data have been used to study the structure and spectra properties of the complex. Full article
Open AccessArticle Theoretical Study on the Interaction of o-Tetrafluorophenylene Mercury with Ethylene and Acetylene
Molecules 2003, 8(5), 418-429; doi:10.3390/80500418
Received: 4 February 2003 / Revised: 17 March 2003 / Accepted: 20 March 2003 / Published: 31 May 2003
PDF Full-text (427 KB) | HTML Full-text | XML Full-text
Abstract
The results of a theoretical study on the interaction of o-tetrafluorophenylene mercury with ethylene and acetylene are reported. The AM1 molecular orbital semiempirical method is applied through a complete optimization procedure without any restrictions to find the optimal equilibrium geometries. The comparative capabilities
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The results of a theoretical study on the interaction of o-tetrafluorophenylene mercury with ethylene and acetylene are reported. The AM1 molecular orbital semiempirical method is applied through a complete optimization procedure without any restrictions to find the optimal equilibrium geometries. The comparative capabilities of ethylene and acetylene molecules to form stable complexes with o-tetrafluorophenylene mercury are analyzed and their corresponding bonding features are discussed. Ethylene seems to be capable of forming a molecular complex while acetylene is predicted to be incapable of doing so. Full article
Open AccessArticle Structures and Chemical Equilibria of Some N-Heterocycles Containing Amide Linkages
Molecules 2003, 8(5), 430-438; doi:10.3390/80500430
Received: 3 July 2002 / Revised: 12 January 2003 / Accepted: 15 April 2003 / Published: 31 May 2003
Cited by 10 | PDF Full-text (250 KB) | HTML Full-text | XML Full-text
Abstract Structures and chemical equilibria of 5-carboxy-2-thiouracil (1), 5,6-diphenyl-3-hydroxy-1,2,4-triazine (2), 1-phenyl-3-methyl-5-pyrazolone (3) and 2-mercapto-4,6-dimethylpyrimidine hydrochloride (4) are reported. Their electronic transitions are assigned and pK values are evaluated and discussed. Full article
Open AccessArticle Synthesis of Some Transition Metal Complexes of a Novel Schiff Base Ligand Derived from 2,2'-bis(p-Methoxyphenylamine) and Salicylicaldehyde
Molecules 2003, 8(5), 439-443; doi:10.3390/80500439
Received: 25 February 2003 / Revised: 3 April 2003 / Accepted: 5 April 2003 / Published: 31 May 2003
Cited by 29 | PDF Full-text (231 KB) | HTML Full-text | XML Full-text
Abstract A novel Schiff base ligand derived from 2,2'-bis(p-methoxyphenylamine) and salicylicaldehyde and its transition metal complexes with Cu (Ⅱ), Co (Ⅱ) and Mn (Ⅱ) have been synthesized. Their spectral properties and electrochemical behavior were investigated. Full article
Open AccessArticle Synthesis of New Pyrazole and Pyrimidine Steroidal Derivatives
Molecules 2003, 8(5), 444-452; doi:10.3390/80500444
Received: 16 April 2003 / Revised: 8 May 2003 / Accepted: 9 May 2003 / Published: 31 May 2003
Cited by 9 | PDF Full-text (285 KB) | HTML Full-text | XML Full-text
Abstract
The synthesis of steroidal heterocycles containing the pyrazole and pyrimidine ring fused to the 16,17-position of the steroid nucleus is reported. Androstenolone acetate (1) reacted with carbon disulfide, iodomethane and sodium hydride to furnish 3β-acetoxy-16-[bis(methylthio)methylene]-5-androst-5-en-17-one (2). The reactions of 2 with hydrazine hydrate
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The synthesis of steroidal heterocycles containing the pyrazole and pyrimidine ring fused to the 16,17-position of the steroid nucleus is reported. Androstenolone acetate (1) reacted with carbon disulfide, iodomethane and sodium hydride to furnish 3β-acetoxy-16-[bis(methylthio)methylene]-5-androst-5-en-17-one (2). The reactions of 2 with hydrazine hydrate and methylhydrazine afforded the 5’-methylthio- pyrazolo[4’,3’:16,17]androst-5-en-3β-ols 3a and 3b, respectively. Treatment of 2 with amidinium, guanidinium, and isothiuronium salts in the presence of sodium methoxide yielded the 6’-methoxy-pyrimido[5’,4’:16,17]androst-5-en-3β-ols (4a-4e). Full article
Open AccessArticle Synthesis and Catalytic Activity of Two New Cyclic Tetraaza Ligands
Molecules 2003, 8(5), 453-458; doi:10.3390/80500453
Received: 11 April 2003 / Revised: 9 May 2003 / Accepted: 9 May 2003 / Published: 31 May 2003
Cited by 1 | PDF Full-text (223 KB) | HTML Full-text | XML Full-text
Abstract Two new chiral cyclic tetraaza ligands were synthesized and characterized. Their catalytic activity was tested in the asymmetric addition of diethylzinc to benzaldehyde. The expected secondary alcohol was obtained in moderate yields, but with very low enantioselectivity. Full article

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