http://localhost:80/xmlui/handle/123456789/19265 2026-03-12T08:56:31Z http://localhost:80/xmlui/handle/123456789/19563 Title: 4+4-methoxybenzoy1)-54-4-methoxypheny1)-2,3-dihydro-2,3-furandione, its Synthesis, Thermolysis and Diels-Alder Reactions with Schiff Bases: Experimental Data and Calculations Authors: SARIPINAR, EMIN; GOZEL, YAHYA; ONAL, ZOLSIYE; ILHAN, ILHAN OZER; AKcAMUR, YUNUS Abstract: p,p'-Dimethoxydibenzoylmethane 1 combines with oxalyl chloride 2 to yield novel furan-2,3-dione 3. Thermal transformation is supposed to occur by the ring opening of the 3 followed by the intermediate p,p'-dimethoxydibenzoylketene IN1 cyclization resulting in the gamma -pyrone IN3. The reaction of 3 with Schiff bases under thermolysis conditions leads to 1,3 oxazinones 5,6. The reaction pathways include formal [4+2] cycloaddition processes, obviously, Electronic structures of reactants, transition states, intermediates and final products of the reaction are calculated by the AM1 method. Transition states was further confirmed by vibrational analysis (computation of force constants analytically) and characterised by the corresponding imaginary vibration modes and frequencies. 2000-12-05T00:00:00Z http://localhost:80/xmlui/handle/123456789/19562 Title: Synthesis of 1,5-Benzodiazepine Nucleosides Authors: 'ROSHAN AHMAD; M. ZIA-UL-HAQ; SHAHID HAMEED; HUMAIRA NADEEM; DUDDECK, HELMUT Abstract: The phenolic beta -diketones I prepared by modified Baker-Venkataraman rearrangement were converted to benzodiazepine derivatives II by treatment with o-phenylenediamine. Coupling of benzodiazepine derivatives II with acetobromo sugars in presence of mercuric cyanide and nitromethane gave acetylated sugar derivatives of benzodiazepines III. The nucleosides IV were obtained by the deacetylation of compounds III. Structures of all intermediates and final products were confirmed with the help of modern spectroscopic methods. 2000-12-04T00:00:00Z http://localhost:80/xmlui/handle/123456789/19561 Title: Use of NMR and Mass Spectrometry in Establishing the Structures of Ring Opening products of 3- Methyl- 4,1- Benzoxazepine-2,5- Dione in Acid and Basic Media Authors: SAMINA ALAM; ZAHEER-UD-DIN BABER; KHAN, NAEEMA Abstract: 3-Methyl-4,1-benzoxazepine-2.5-dione (I) when stirred for lr hours in methanolic solution with a few drops of 10 %. NaOH below 60 degreesC gave solid crystalline product (m.p. 100-102 degreesC, 51% yield). H-1 NMR and MS analysis confirmed structure (II) which suggest the cleavage of C-O bond but when (I) was treated with a few drops of 10% HCl under similar temperature yielded compound (III) as a liquid which gave evidence for C-N bond cleavage giving no traces of the former product (II). 2000-12-03T00:00:00Z http://localhost:80/xmlui/handle/123456789/19560 Title: Synthesis and Characterization of the Nickel and Cobalt Complexes of New BF2+ Bridged, 1,2-Benzoquinone Bis (a-Dioxime) Macrocycles Authors: AHMAD S. ABUSHAMLEH; MUSTAFA M. EL-ABADELAH Abstract: The synthesis, characterization and structure of new cobalt and nickel complexes with a BF2+ bridged, bis (1,2-dione dioxime) ligand based on benzoquinone are described. The crystal structure of the bis (BF2+) bridged nickel complex has space group C2/c (#15) with unit cell dimensions a = 19.000 (2), b = 5.452 (2), c = 16.357 (1) A,Beta = 119.251 (7)degrees, V = 1519.8 (2) A(3), Z = 4, R-i = 0.043 and wR(2) = 0.052. The ligand provides strong field and the complexes are diamagnetic. The spectral properties of the complexes are discussed. 2000-12-08T00:00:00Z