Home About us Contact
|
Home About us Contact | ||
|
|
||
Cyclocondensation Reaction (cyclocondensation + reaction)
Selected AbstractsNovel Biginelli-Like Three-Component Cyclocondensation Reaction: Efficient Synthesis of 5-Unsubstituted 3,4-Dihydropyrimidin-2(1H)-ones.CHEMINFORM, Issue 4 2005Zong-Ting Wang Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Arenesulfonylimines of Methyl Trifluoropyruvate in the Cyclocondensation Reactions with 1,3-C,N- and -N,N-Binucleophiles.CHEMINFORM, Issue 40 2008V. B. Sokolov Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Synthesis of some pyrazole-3-carboxylic acid-hydrazide and pyrazolopyridazine compoundsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2005Furan-2,3-diones 1a-c react with various hydrazines 2a-c under different conditions to yield the pyrazole-3-carboxylic acid-hydrazide 3a-d. Cyclocondensation reactions of 1a or 7 with phenylhydrazine lead to derivatives of pyrazolo[3,4- d]pyridazinones 6 and 8, respectively. The structures of all products were confirmed by elemental analysis, IR, 1H- and 13C-NMR spectroscopic measurements. [source] An Efficient Synthesis of Novel Hexahydropyrido[2,3- d]pyrimidine Derivatives from (Arylmethylidene)pyruvic Acids (=(3E)-4-Aryl-2-oxobut-3-enoic Acids) in Aqueous MediaHELVETICA CHIMICA ACTA, Issue 5 2009Saeed Balalaie Abstract A series of new hexahydropyrido[2,3- d]pyrimidine derivatives 3 were synthesized by the cyclocondensation reaction of (arylmethylidene)pyruvic acids (=(3E)-4-aryl-2-oxobut-3-enoic acids) 1 and 6-aminouracils (=6-aminopyrimidine-2,4(1H,3H)-diones) 2 in H2O under reflux conditions (Scheme,1, Table). This novel protocol has the advantages of facility, of easy workup, of high yields, and of an environmentally benign procedure. The structures of compounds 3a,3f were corroborated spectroscopically (IR, 1H- and 13C-NMR, and EI-MS). A plausible mechanism for the reaction is proposed (Scheme,2). [source] Synthesis and some reactions of 4-(ethoxycarbonyl)-1,5-diphenyl-1H -pyrazole-3-carboxylic acidJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2007Ahmet, ener 1,5-Diphenyl-1H -pyrazole-3,4-dicarboxylic acid-4-ethyl ester 2, obtained from the 4-ethoxycarbonyl-5-phenyl-2,3-furandione 1 and N -benzylidene- N,-phenyl hydrazine, was converted via reactions of its acid chloride 3 with various alcohols or N-nucleophiles into the corresponding ester 5 or amide derivatives 6, respectively. In addition, 2 was decarboxylated to give ethyl 1,5-diphenylpyrazole-4-carboxylate 4. Nitrile 7 derivative of 2 was also obtained by dehydration of 6a in a mixture of SOCl2 and DMF. While cyclocondensation reaction of 2 with hydrazine hydrate leads to the formation of pyrazolo[3,4- d]pyridazine-4,7-dione 8, the reaction of 3 with anhydrous hydrazine provided a new bis pyrazole derivative 9. [source] Regiospecific synthesis of trichloromethyl substituted 4,5-dihydro-1h -1-tosylpyrazolesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2007Helio G. Bonacorso The regiospecific synthesis of a new series of eight 3-alkyl(aryl)-5-hydroxy-5-trichloromethyl-4,5-dihydro-1H -1-tosylpyrazoles is reported. The 1- p -tosyl-2-pyrazolines were obtained from the cyclocondensation reaction of 4-alkyl(aryl)-4-alkoxy-1,1,1-trichloroalk-3-en-2-ones, [where alkyl = H, Me and aryl = -C6H5, 4-CH3C6H4, 4-OCH3C6H4, 4-FC6H4, 4-ClC6H4, 4-BrC6H4,] with p -tosylhydrazine in 64 to 92 % yields, employing anhydrous toluene at reflux or diethyl ether at room temperature as the reaction condition. [source] Reactions of 6-aminopyrimidines with 2-dimethylaminomethylenetetralone.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 2 20015- b] quinolines, 6-Dihydrobenzo [h]pyrimido [, Regiospecific Synthesis Of Benzo[h]pyrimido[4,5- b]quinolines (3) have been synthesized via a regiospecific cyclocondensation reaction between 6-aminopyrimidines (1) and 2-dimethylaminomethylentetralone hydrochloride (2). The linear structure of the final compounds were determined by nmr measurements, especially by 1H,1H, 1H,13C COSY and DEPT experiments. [source] (9E)-9-Benzylidene-3-methyl-2-methylsulfanyl-5-phenyl-5,6,7,8,9,10-hexahydropyrimido[4,5- b]quinolin-4(3H)-one: polarized molecules within hydrogen-bonded bilayersACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2010Diana Becerra The molecules of the title compound, C26H25N3OS, which was prepared by means of an acid-catalysed cyclocondensation reaction between a 6-aminopyrimidinone and 2,6-dibenzylidenecyclohexanone, exhibit a polarized electronic structure, namely (9E)-9-benzylidene-3-methyl-2-methylsulfanyl-5-phenyl-3,5,6,7,8,9-hexahydropyrimido[4,5- b]quinolin-10-ium-4-olate, involving charge separation in the vinylogous amide portion. Four hydrogen bonds, two each of the C,H...O and C,H...,(arene) types, link the molecules into bilayers comprising inversion-related pairs of sheets, each containing a single type of R43(36) ring. [source] Me3SiCl and Et3SiI-promoted one-pot synthesis of 1,4-dihydropyridine derivativesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 7 2009Maryam Mirza-Aghayan Abstract An efficient synthesis of 1,4-dihydropyridine derivatives has been achieved by the one-pot cyclocondensation reaction of methyl 3-aminocrotonate and a range of aldehydes in the presence of chlorotrimethylsilane as a promoter under solvent-free conditions. The cyclocondenstion reaction requires a very short time and takes place in good to excellent yields. Furthermore iodotriethylsilane, generated in situ by the reaction of triethylsilane and methyl iodide in the presence of palladium chloride, has been investigated for the synthesis of 1,4-dihydropyridine derivatives. This facile and efficient method affords high yields for the preparation of 1,4-dihydropyridines at room temperature and short reaction times. Copyright © 2009 John Wiley & Sons, Ltd. [source] Dynamic Kinetic Resolution and Desymmetrization Processes: A Straightforward Methodology for the Enantioselective Synthesis of PiperidinesCHEMISTRY - A EUROPEAN JOURNAL, Issue 30 2006Mercedes Amat Prof. Abstract A straightforward procedure for the synthesis of enantiopure polysubstituted piperidines is reported. It involves the direct generation of chiral non-racemic oxazolo[3,2- a]piperidone lactams that already incorporate carbon substituents on the heterocyclic ring and the subsequent removal of the chiral auxiliary. The key step is a cyclocondensation reaction of (R)-phenylglycinol or other amino alcohols with racemic or prochiral ,-oxo (di)acid derivatives in highly stereoselective processes involving dynamic kinetic resolution and/or desymmetrization of diastereotopic or enantiotopic ester groups. Se describe un procedimiento directo para la síntesis enantioselectiva de piperidinas polisustituidas. Consiste en la generación directa de oxazolo[3,2-a]piperidonas quirales no racémicas que ya incorporan sustituyentes carbonados en las diferentes posiciones del heterociclo, y en la posterior eliminación del auxiliar quiral. La etapa clave es una reacción de ciclocondensación entre el (R)-fenilglicinol, u otros amino alcoholes quirales, con derivados de , -oxo ácidos racémicos o proquirales, en procesos altamente estereoselectivos que implican una resolución cinética dinámica y/o la desimetrización de grupos diastereotópicos o enantiotópicos. [source] Synthesis and Structural Characterization of 1,4-Di(2-methoxyphenyl)-2,5-piperazinedioneCHINESE JOURNAL OF CHEMISTRY, Issue 5 2007Shu-Sheng Zhang Abstract A new derivative of 2,5-piperazinedione, 1,4-di(2-methoxyphenyl)-2,5-piperazinedione (I), was synthesized by the cyclocondensation reaction of N -2-methoxyphenyl chloroacetamide, and its structure was characterized by elemental analysis, IR, 1H NMR and single crystal X-ray diffraction method. The crystal belongs to monoclinic system, space group P21/c with unit cell dimensions a=0.56934(10) nm, b=1.3880(2) nm, c=1.00329(17) nm, ,=90.376(3)°, V=0.7928(2) nm3, Z=2, Dc=1.367 g·cm,3, ,=0.98 cm,1, R and wR being 0.0606 and 0.1564 respectively for 1549 unique reflections with 1247 observed reflections [I>2,(I)]. The molecule has a crystallographically imposed symmetry center. The three rings in the molecule are each coplanar with their attached groups, excluding methyl H atoms and the H atoms attached to the piperazinedione ring, while the whole molecule is not planar, with dihedral angles of 74.7(1)° between the piperazinedione and each of the two aromatic rings. The crystal structure is stabilized by van der Waals and dipole-dipole forces. [source] Solvent-free route to ,-enamino dichloromethyl ketones and application in the synthesis of novel 5-dichloromethyl-1H -pyrazolesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2009Marcos A. P. Martins An efficient procedure to prepare a series of five 4-amino-1,1-dichloro-3-penten-2-ones [CHCl2C(O)CHC(Me)NR1R2, where R1/R2 = H/Ph, H/Bn, H/CH2CH2OH, (CH2)4,(CH2)2O(CH2)2] from the solvent-free reaction of 1,1-dichloro-4-methoxy-3-penten-2-one with primary and secondary amines is reported. 1,1-Dichloro-4-methoxy-3-penten-2-one was reacted with hydrazine hydrochloride, phenylhydrazine hydrochloride and semicarbazide hydrochloride to obtain 5-dichloromethyl-3-methylpyrazoles. Aminoguanidine hydrochloride and 1,2-dimethylhydrazine dihydrochloride were also reacted with 1,1-dichloro-4-methoxy-3-penten-2-one to obtain 5-dichloromethyl-3-methylpyrazoline and 5-dichloromethyl-1,2,3-trimethyl pyrazolium chloride, respectively. All cyclocondensation reactions were performed in one-pot procedures. J. Heterocyclic Chem., (2009). [source] Studies on the reactions of cyclic oxalyl compounds with hydrazines or hydrazones : Synthesis and reactions of 4-benzoyl-1-(3-nitrophenyl)-5-phenyl-1H -pyrazole-3-carboxylic acidJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2002Ahmet, ener The 1H -pyrazole-3-carboxylic acid 2, obtained from the furan-2,3-dione 1 and N -Benzylidene- N'-(3-nitrophenyl) hydrazine, was converted via reactions of its acid chloride 3 with various alcohols or N-nucleo-philes into the corresponding ester or amide derivatives 4 or 5, respectively. Nitrile 6 and anilino-pyrazole acid 7 derivatives of 2 were also obtained by dehydration of 5a in a mixture of SOCl2 with DMF and reduction of 2 with sodium polysulphide, respectively. While cyclocondensation reactions of 2 or 7 with phenyl hydrazine or hydrazine hydrate and 6 with only anhydrous hydrazine lead to derivatives of pyrazolo[3,4- d]-pyridazinone 8 and pyrazolo[3,4- d]pyridazine amine 9, respectivel. The reaction of 2 with 2-hydrazinopyri-dine provided hydrazono-pyrazole acid derivative 10, which was decarboxylated to give hydrazono-pyra-zole derivative 11. Pyrazolo[4,3- d]oxazinone 12 and 2-quinolyl pyrazolo[3,4- d]pyridazine 13 derivatives were also prepared by cyclocondensation reactions of 2 with hydroxylamine hydrochloride and 7 with acetaldehyde, respectively. [source] | ||||||||||||||||||||||