Display options:
Normal
Show Abstracts
Compact
Displaying article 1-7
p. 401-410
Received: 26 November 2002; in revised form: 6 April 2003 / Accepted: 9 April 2003 / Published: 31 May 2003
Show/Hide Abstract
| Download PDF Full-text (291 KB) 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 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.
p. 411-417
Received: 9 February 2003; in revised form: 3 April 2003 / Accepted: 6 April 2003 / Published: 31 May 2003
Show/Hide Abstract
| Download PDF Full-text (333 KB) 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 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.
p. 418-429
Received: 4 February 2003; in revised form: 17 March 2003 / Accepted: 20 March 2003 / Published: 31 May 2003
Show/Hide Abstract
| Download PDF Full-text (427 KB) 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 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.
p. 430-438
Received: 3 July 2002; in revised form: 12 January 2003 / Accepted: 15 April 2003 / Published: 31 May 2003
Show/Hide Abstract
| Download PDF Full-text (250 KB) 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.
p. 439-443
Received: 25 February 2003; in revised form: 3 April 2003 / Accepted: 5 April 2003 / Published: 31 May 2003
Show/Hide Abstract
| Download PDF Full-text (231 KB) 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.
p. 444-452
Received: 16 April 2003; in revised form: 8 May 2003 / Accepted: 9 May 2003 / Published: 31 May 2003
Show/Hide Abstract
| Download PDF Full-text (285 KB) 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 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).
p. 453-458
Received: 11 April 2003; in revised form: 9 May 2003 / Accepted: 9 May 2003 / Published: 31 May 2003
Show/Hide Abstract
| Download PDF Full-text (223 KB) 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.
Displaying article 1-7
Plain Text
BibTeX
BibTeX (without abstracts)
Endnote
Endnote (without abstracts)
Tab-delimited
PubMed XML
DOAJ XML
AGRIS XML
to open them.