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Catalyzed Cyclization (catalyze + cyclization)
Selected AbstractsSynthesis of Tyrosine-Derived Tetrahydroisoquinolines by Lewis Acid Catalyzed Cyclization of N -(Phenylsulfonyl)alkyloxazolidinones,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 33 2007Stefan Tussetschläger Abstract N -Boc-protected tyrosine esters 5a,b were converted into tetrahydroisoquinolines 13 and 14 in four steps by reduction and ring closure to oxazolidinones 9 and 10, addition of benzenesulfinic acid and aldehydes to sulfones 11 and 12 and subsequent Lewis acid catalyzed cyclization. In the case of m -tyrosine derivative 5a, selective protection with bromine prevented the formation of undesired regioisomers. Debromination of target compounds 13 was readily achieved under radical reduction conditions by using Bu3SnH/AIBN. Tetrahydroisoquinolines 13 and 14 were isolated as single diastereomers whose trans configuration was confirmed by X-ray crystal structure analysis. Partial epimerization of trans - 13i and trans - 21 to the corresponding cis diastereomers was achieved under basic conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Ruthenium(II)-Catalyzed Cyclization of Oxabenzonorbornenes with Propargylic Alcohols: Formation of IsochromenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2006Karine Villeneuve Abstract The ruthenium-catalyzed cyclization of a propargylic alcohol with an oxabenzonorbornene in methanol leads to an unanticipated isochromene framework. The catalytic cycle to form this product is believed to go through an oxidative cyclization of the two unsaturated partners with the ruthenium catalyst, followed by ,-hydride elimination, tautomerization andhydroruthenation. The ruthenacyclobutane thus obtained further undergoes [2+2] cycloreversion to form a ruthenium,carbene intermediate that atypically rearranges via a [1,3]-alkoxide shift and finally reductively eliminates to produce the desired compound. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Sulfur-Assisted and 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU)-Catalyzed Cyclization of 2-Alkynylanilines for the Metal-Free Synthesis of Indole DerivativesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010Hongwei Zhou Abstract A sulfur-assisted and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-catalyzed cyclization of 2-alkynylanilines for the metal-free synthesis of indole derivatives is reported. As a result of the metal-free process, the ready availability of the starting materials and the simple and convenient operation, the type of reaction presented here has potential utility in organic synthesis. A 10-gram scale preparation may demonstrate the possibility of its application in the environmentally friendly synthesis of indole derivatives. [source] Synthesis of (E)-3-Alkylidene-1-pyrrolines by the Rhodium- Catalyzed Cyclization of Terminal Alkynes with Homopropargylic AminesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Yoshiya Fukumoto Abstract The cyclization of terminal alkynes with homopropargylic amines in the presence of a rhodium complex as catalyst leads to the formation of (E)-3-alkylidene-1-pyrrolines. The reaction tolerates a wide range of functional groups on the terminal alkynes. The formation of a vinylidene-rhodium complex, followed by the intermolecular nucleophilic attack of a homopropargylic amine nitrogen on the ,-carbon atom of the vinylidene-rhodium complex, is proposed as a key step in the catalytic reaction. [source] Synthesis of Trisubstituted Pyrroles from Rhodium-Catalyzed Alkyne Head-to-Tail Dimerization and Subsequent Gold- Catalyzed CyclizationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Hong Mei Peng Abstract Dimerization of N -protected propargylic amines in a rather rare head-to-tail mode has been achieved under mild conditions with high selectivity using rhodium catalysts. The N -protecting group could be a sulfonyl, carbamate, or carbonyl functionality and (cyclooctadiene)rhodium chloride dimer/1,1,-bis(diphenylphosphino)ferrocene {[Rh(COD)Cl]2/dppf} as well as tris(triphenylphosphine)rhodium chloride [Rh(PPh3)3Cl] proved to be active catalysts. In addition, these functionalized gem -enynes subsequently undergo selective gold(III)-catalyzed intramolecular hydroamination to give trisubstituted pyrroles under mild conditions. [source] Synthesis of 2,6-Dioxo-1,2,3,4,5,6-hexahydroindoles by Acid- Catalyzed Cyclization of Acetal-Protected (2,4-Dioxocyclohex-1-yl)acetamides and their Transformation into 5,8,9,10-Tetrahydro-6H -indolo[2,1- a]isoquinolin-9-onesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2009Benard Juma Abstract Acetal-protected (2,4-dioxocyclohex-1-yl)acetic acids were prepared by allylation of dilithiated 1,3-cyclohexane-1,3-diones, protection of the carbonyl groups and oxidation of the alkene moiety. Their reaction with amines afforded the corresponding amides which were transformed, by acid-catalyzed cyclization, into various 2,6-dioxo-1,2,3,4,5,6-hexahydroindoles. The reaction of the latter with triflic acid resulted in the formation of novel 5,8,9,10-tetrahydro-6H -indolo[2,1- a]isoquinolin-9-ones. [source] ChemInform Abstract: AgNO3 -Catalyzed Cyclization of Propargyl-Meldrum,s Acids in Aqueous Solvent: Highly Selective Synthesis of Z-,-Alkylidene Lactones.CHEMINFORM, Issue 52 2009Wei Jia 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] ChemInform Abstract: An Efficient Synthesis of Carbazoles from PtCl2 -Catalyzed Cyclization of 1-(Indol-2-yl)-2,3-allenols.CHEMINFORM, Issue 50 2009Wangqing Kong 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] ChemInform Abstract: Intramolecular Pd(II)-Catalyzed Cyclization of Propargylamides: Straightforward Synthesis of 5-Oxazolecarbaldehydes.CHEMINFORM, Issue 42 2008Egle M. Beccalli 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] The Use of Iminopyridines as Efficient Ligands in the Palladium(II)-Catalyzed Cyclization of (Z)-4,-Acetoxy-2,-butenyl 2-Alkynoates.CHEMINFORM, Issue 38 2007Juan Song 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, please click on HTML or PDF. [source] W(CO)5(L)-Catalyzed Cyclization of ,-Acetylenic Silyl Enol Ethers for the Preparation of Nitrogen-Containing Cyclic Compounds.CHEMINFORM, Issue 27 2007Antoine Grandmarre 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, please click on HTML or PDF. [source] Preparation of Substituted Cyclopentadienes Through Platinum(II)-Catalyzed Cyclization of 1,2,4-Trienes.CHEMINFORM, Issue 18 2007Hideaki Funami 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, please click on HTML or PDF. [source] Synthesis of Functionalized ,3 -Pyrrolines via a Ag(I)-Catalyzed Cyclization of Amino Acid Derived Allenes.CHEMINFORM, Issue 14 2007Branko Mitasev 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, please click on HTML or PDF. [source] Au(I)-Catalyzed Cyclization of tert-Butyl Carbonates Derived from Homopropargyl Alcohols: A Catalytic Alternative to Cyclic Enol Carbonates.CHEMINFORM, Issue 29 2006Ji-Eun Kang 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, please click on HTML or PDF. [source] Cationic Palladium Complex Catalyzed Cyclization,Hydrosilylation of 1,6-Heptadiyne and Its Homologues.CHEMINFORM, Issue 8 2004Takanori Uno Abstract For Abstract see ChemInform Abstract in Full Text. [source] Studies on Pd0 -Catalyzed Cyclization of N -3,4-Alkadienyl Toluenesulfonamides with Organic Halides: Selective Synthesis of 2,3-Dihydropyrroles, 1,2,3,6-Tetrahydropyrridines, and AzetidinesCHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2007Shengming Ma Prof. Abstract The palladium-catalyzed coupling,cyclization of ,-amino allenes with organic halides ranging from aryl halide to 1-alkenyl halide was studied. 2,3-Dihydro-1H -pyrroles were obtained by reaction of 3-substituted-5-unsubstituted-3,4-allenyl amides under conditions A, while the reaction of 5-substituted-3,4-allenyl amides afforded 1,2,5,6-tetrahydropyridines and/or azetidines with high de under conditions B or C. The skeleton and relative configuration of the six-membered products were established by the X-ray diffraction studies of 10,ka. Allenyl amide 4,q reacted with 1,4-diiodobenzene 6,r to afford double cyclization product 15. The structure of its major stereoisomer was also determined by the X-ray diffraction study. 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