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Cyclization Products (cyclization + products)

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Chemistry100%

Selected Abstracts

An Efficient and Diastereoselective Intramolecular 1,3-Dipolar Cycloaddition of Cyclic Azomethine Ylides and Nitrones

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2006
Rafael Pedrosa
Abstract Nitrones and azomethine ylides formed by condensation of chiral 2-formyl-perhydro benzoxazines and N -substituted hydroxylamines or cyclic ,-amino acids cyclize intramolecularly yielding polycyclic isoxazolidine or pyrrolidine derivatives, respectively, with total diastereoselectivity. On the contrary, stabilized azomethine ylides derived from methyl prolinate undergo the cyclization products in very low yields.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Synthesis of 1,3-Difunctionalized Cyclopentenes and 1,3,5-Trifunctionalized Cyclohexanes by Silicon-Induced Domino Reactions

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2003
Frank Tries
Abstract A novel domino process based on a 1,4-C,O shift of a silyl group (4 , 3) and a Michael-induced ring-closure reaction (3 , 2) is investigated. Specifically, attack of carbanions 5 on vinyloxiranes 6 usually occurs on the oxirane unit to give the desired silyl shift. When starting from vinyloxiranes 6a and 6b, however, the reaction stops at this stage to give silyl ethers 7. Sulfur (6c) or silicon activation (6d,f) of the C=C unit is required to yield cyclopentenes 1a,d. Analogously, carbanion 5a and allyloxiranes 15 give cyclization products 19,22, particularly if the ring-closure step is supported by silicon substitution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Synthesis and biological activity of 3-[(6-chloropyridin-3-yl)methyl]-6-substituted-6,7-dihydro-3H -1,2,3-triazolo[4,5- d]-pyrimidin-7-imines

JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2008
Xiao-Bao Chen
A series of 3-[(6-chloropyridin-3-yl)methyl]-6-substituted-6,7-dihydro-3H -1,2,3-triazolo[4,5- d]pyrimidin-7-imines were designed and synthesized via a multi-step sequence using 2-chloro-5-(chloromethyl)-pyridine as the starting material. Various primary aliphatic amines, hydrazine and hydrazide reacted with 3 to obtain the cyclization products 4. Their structures were confirmed by 1H NMR and elemental analyses, some of them were also confirmed by IR, 13C NMR, MS and single crystal X-ray diffraction. The preliminary bioassay indicated that some of the target compounds 4 displayed moderate to weak fungicidal activity and insecticidal activity. [source]

Synthesis and NMR spectroscopic studies of allylsulfanyl- N1 -alkyl- N4 -phenyl-1,4-phenylenediamines and their cyclization products, 2,3-dihydro-1-benzothiophenes and thiochromans

MAGNETIC RESONANCE IN CHEMISTRY, Issue 12 2004
Alan R. Katritzky
Abstract Regioselective addition of allylthiol at the C-3 position adjacent to the nitrogen carrying the phenyl group of the 1,4-phenylenediamine moiety of compounds 1,4 was rigorously confirmed by 1D NOE difference in combination with gHMBC experiments. The structures of 1,4-phenylenediamines 1,4, allylsulfanyl- N1 -alkyl- N4 -phenyl-1,4-phenylenediamines 5,8 and cyclization products 9,14 were completely analyzed in both CDCl3 and DMSO- d6 solutions. The 1H and 13C NMR spectra of 10 and 11, which contain two chiral centers, exhibit duplication for several signals, indicating the existence of two diastereomeric forms. The full structures of 5 and 9 were unambiguously confirmed by x-ray crystallography. The 1H and 13C NMR spectra of all compounds were assigned using one- and two-dimensional NMR techniques (APT, DEPT, 1D NOE difference, COSY, NOESY, HETCOR, gHMQC and gHMBC). Copyright © 2004 John Wiley & Sons, Ltd. [source]

ChemInform Abstract: Rhodium-Catalyzed Chemo- and Stereoselective Arylative and Alkenylative Cyclization Reactions of Unsymmetric Diynes Containing a Terminal Alkyne Moiety with Organoboronic Acids.

CHEMINFORM, Issue 38 2010
Levent Artok
Abstract A variety of 1,6-diynes containing a terminal alkyne, e.g. (I) or (IV), reacts with aryl- (II) or alkenylboronic acids (VI) with excellent chemo- and stereoselectivity in the presence of a Rh2(cod)2(O-Me)2 complex to give the 5-exo cyclization products, exclusively. [source]