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Selected AbstractsHighly Enantioselective Conjugate Addition of Ketones to Alkylidene Malonates Catalyzed by a Pyrrolidinyl,Camphor-Derived OrganocatalystEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2010Dhananjay R. Magar Abstract Pyrrolidinyl,camphor derivatives have been proven to be efficient organocatalysts for enantioselective conjugate addition of ketones to alkylidene malonates, affording high chemical yields (up to 95,%) of the corresponding products with high to excellent levels of diastereoselectivity (up to >99:1,dr) and enantioselectivity (up to 96,%,ee) under solvent-free reaction conditions at ambient temperature. [source] Reactions of Chlorosulfanyl Derivatives of Cyclobutanones with Different NucleophilesHELVETICA CHIMICA ACTA, Issue 5 2006Agnieszka Majchrzak Abstract The reactions of 3-chloro-3-(chlorosulfanyl)-2,2,4,4-tetramethylcyclobutan-1-one (2) with N, O, S, and P nucleophiles occur by substitution of Cl at the S-atom. Whereas, in the cases of secondary amines, alkanols, phenols, thiols, thiophenols, and di- and trialkyl phosphates, the initially formed substitution products were obtained, the corresponding products with allyl and propargyl alcohols undergo a [2,3]-sigmatropic rearrangement to give allyl and allenyl sulfoxides, respectively. Analogous substitution reactions were observed when 3-chloro-3-(chlorodisulfanyl)-2,2,4,4-tetramethylcyclobutan-1-one (3) was treated with N, O, and S nucleophiles. The reaction of 3 with Et3P led to an unexpected product via cleavage of the SS bond (cf. Scheme,13). In the reactions of 2 with primary amines and H2O, the substitution products react further via elimination of HCl to yield the corresponding thiocarbonyl S -imides and the thiocarbonyl S -oxide, respectively. Whereas the latter could be isolated, the former were not stable but could be intercepted by MeOH (Scheme,4) or adamantanethione (Scheme,5). The structures of some of the substitution products were established by X-ray crystallography. [source] Doubly Stereocontrolled Asymmetric Aza-Henry Reaction with in situ Generation of N -Boc-Imines Catalyzed by Novel Rosin-Derived Amine Thiourea CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009Xianxing Jiang Abstract The doubly stereocontrolled organocatalytic aza-Henry reaction of nitroalkanes to N -Boc-imines generated in situ from a variety of substituted ,-amido sulfones was investigated for the first time, in general, affording the corresponding products with high to excellent yields (up to 93% yield) and enantioselectivities (up to 98% ee), and satisfactory diastereoselectivies (anti/syn up to 98:2). Furthermore, these organocatalysts based on rosin have been proved to be the very effective promoters for this catalytic asymmetric process along side the Cinchona alkaloid-derived catalysts. [source] Synthesis of N-Heteroaryl(trifluoromethyl)hydroxyalkanoic Acid Esters by Highly Efficient Solid Acid-Catalyzed Hydroxyalkylation of Indoles and Pyrroles with Activated Trifluoromethyl KetonesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14 2005Mohammed Abid Abstract The synthesis of N-heteroaryl(trifluoromethyl)hydroxyalkanoic acid esters by solid acid-catalyzed Friedel,Crafts hydroxyalkylation of indoles and pyrroles with ethyl 3,3,3-trifluoropyruvate and ethyl 4,4,4-trifluoroacetoacetate is described. The inexpensive and readily available K-10 montmorillonite is found to be an efficient catalyst for the synthesis of a wide variety of trifluoromethylated indol-3-yl- and pyrrol-2-yl-hydroxypropionic and -butanoic acid esters. Using a series of substituted indoles and pyrroles the corresponding products were isolated in excellent yield (up to 98%) and 100% selectivity under mild experimental conditions, during very short reaction times. Beyond these, the ease of product isolation, catalyst stability and handling make this process an attractive, environmentally benign alternative for the synthesis of the target compounds. [source] Exploration of amino-functionalized ionic liquids as ligand and base for Heck reactionAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 5 2010Jie Liu Abstract A kind of amino-functionalized ionic liquid has been prepared and investigated as ligand and base for the Heck reactions between aryl iodides and bromides with olefins in the presence of a catalytic amount of Pd submicron powder in [Bmim]PF6. The reactions generated the corresponding products in excellent yields under mild reaction conditions. The generality of this catalytic system to the different substrates also gave satisfactory results. The key feature of the reaction is that Pd species and ionic liquids were easily recovered and reused six times with constant activity. Copyright © 2010 John Wiley & Sons, Ltd. [source] CuI/PPh3 -catalyzed Sonogashira coupling reaction of aryl iodides with terminal alkynes in water in the absence of palladiumAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 2 2009Jin Tao Guan Abstract The Sonogashira cross-coupling of aryl iodides with terminal alkynes catalyzed by a simple and inexpensive catalyst system of CuI/PPh3 in water as the sole solvent has been reported. In the presence of CuI/PPh3, with KOH used as a base, a number of aryl iodides were treated with alkynes to afford the corresponding products in moderate to excellent yields. Copyright © 2008 John Wiley & Sons, Ltd. [source] ChemInform Abstract: Expeditious Synthesis of Benzopyrans via Lewis Acid-Catalyzed C,H Functionalization: Remarkable Enhancement of Reactivity by an ortho Substituent.CHEMINFORM, Issue 34 2010Keiji Mori Abstract ortho-Substitution to the alkoxy group enhances the reactivity of the substrates and leads to the higher yields of the corresponding products [cf. [source] Gold(I)-Catalyzed Intermolecular Hydroarylation of Alkenes with Indoles under Thermal and Microwave-Assisted ConditionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 27 2008Ming-Zhong Wang Abstract An efficient method for intermolecular hydroarylation of aryl and aliphatic alkenes with indoles using a combination of [(PR3)AuCl]/AgOTf as catalyst under thermal and microwave-assisted conditions has been developed. The gold(I)-catalyzed reactions of indoles with aryl alkenes were achieved in toluene at 85,°C over a reaction time of 1,3,h with 2,mol,% of [(PR3)AuCl]/AgOTf as catalyst. This method works for a variety of styrenes bearing electron-deficient, electron-rich, and sterically bulky substituents to give the corresponding products in good to high yields (60,95,%). Under microwave irradiation, coupling of unactivated aliphatic alkenes with indoles gave the corresponding adducts in up to 90,% yield. Selective hydroarylation of terminal CC bond of conjugated dienes with indoles gave good product yields (62,81,%). On the basis of deuterium-labeling experiments, a reaction mechanism involving nucleophilic attack of Au(I)-coordinated alkenes by indoles is proposed. [source] Asymmetric aldol reactions catalyzed by efficient and recyclable silica-supported proline-based peptidesCHIRALITY, Issue 4 2009Jincan Yan Abstract A series of silica-supported proline-based peptides were synthesized and applied as catalysts for direct asymmetric intermolecular aldol reactions. Among these, a peptide with two L -proline units was found to be the most efficient one for the asymmetric aldol reactions between acetone and aromatic aldehydes. The reactions generated the corresponding products with satisfactory isolated yields (up to 97%) and enantiomeric excesses (up to 96%) in the presence of this catalyst (5 mol %). Furthermore, the silica-supported organocatalyst could be recovered and recycled by a simple filtration of the reaction solution and used for five consecutive trials without loss of its reactivity. Chirality, 2009. © 2008 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||