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Good-to-excellent Yields (good-to-excellent + yield)
Selected AbstractsSuzuki,Miyaura Coupling Reaction of Boronic Acids and Ethyl Glyoxylate: Synthetic Access to Mandelate DerivativesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 34 2008Irene Notar Francesco Abstract The palladium-catalyzed coupling reaction of arylboronicacids with ethyl glyoxylate provides a straightforward method for the synthesis of mandelic esters. Pd2(dba)3·CHCl3 in combination with 2-di- tert -butylphosphanylbiphenyl as the catalytic system and Cs2CO3 as the base were used. The reaction tolerates a wide range of functionalized boronicacids. Mandelic esters were isolated in good-to-excellent yields with a variety of neutral, slightly electron-rich, and slightly electron-poor substituents.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] An Efficient Approach for the Synthesis of N-1 Substituted HydantoinsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2008Vinod Kumar Abstract An efficient three-step route for the synthesis of N - 1 alkyl/aryl-substituted hydantoins was developed from inexpensive commercially available substrates. The reaction of amines with cyanogen bromide takes place to give monoalkyl/aryl cyanamides. This on treatment with methyl bromoacetate in the presence of sodium hydride in tetrahydrofuran affords methyl N -cyano- N -alkyl/arylaminoacetate, which undergoes hydrolysis and cyclization in the presence of 50,% H2SO4 to afford N - 1 substituted hydantoins in very good-to-excellent yields. Wide varieties of final products having primary, secondary, tertiary, and aryl substituents at the N - 1 position were successfully synthesized by this method. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Reaction of Hydantoin with Boronic AcidsHELVETICA CHIMICA ACTA, Issue 6 2010Abstract We have examined the reaction of hydantoin (=imidazolidine-2,4-dione) with (formylphenyl)boronic acids, where the addition of a boronic acid group is hoped to increase bioactivities. Addition of (2-formylphenyl)boronic acid to hydantoin gave an unexpected azaborine compound, which presumably arises by initial formation of the (phenylmethylidene)hydantoin, with subsequent loss of H2O to give the cyclized product. Reactions of (3-formylphenyl)- and (4-formylphenyl)boronic acids with hydantoin gave the corresponding [(Z)-phenylmethylidene]hydantoins in good-to-excellent yields. Attempts to use (3-formylthiophen-2-yl)boronic acid gave a product where the boronic acid group has been cleaved. [source] Synthesis of Novel Polycyclic Indole-Annulated Thiopyranocoumarin Derivatives via Domino Knoevenagel,Hetero- Diels,Alder Reaction in Aqueous MediaHELVETICA CHIMICA ACTA, Issue 5 2010Firouz, Matloubi Moghaddam Abstract An efficient synthesis of polycyclic indole derivatives is achieved via domino Knoevenagel,hetero- Diels,Alder reaction of O -acrylated salicylaldehyde derivatives with dihydroindole-2-thiones in H2O as solvent. The products are formed in good-to-excellent yields with high regio- and stereoselectivity. [source] An Efficient N -Arylation of Heterocycles with Aryl-, Heteroaryl-, and Vinylboronic Acids Catalyzed by Copper FluorapatiteHELVETICA CHIMICA ACTA, Issue 5 2010Lakshmi Kantam, Mannepalli Abstract N -Arylation of N-containing heterocycles, such as pyrazoles, imidazoles, and benzimidazoles with aryl-, heteroaryl-, and vinylboronic acids was efficiently carried out by copper fluorapatite (CuFAP) catalyst in MeOH at room temperature under base-free conditions. The N- arylated heterocycles were isolated in good-to-excellent yields. [source] Multicomponent Approach Towards the Synthesis of Substituted Pyrroles under Supramolecular Catalysis Using , -Cyclodextrin as a Catalyst in Water Under Neutral ConditionsHELVETICA CHIMICA ACTA, Issue 10 2009Narayana Murthy, Sabbavarapu Abstract Synthesis of substituted pyrroles in H2O by using , -cyclodextrin as a supramolecular catalyst is described. This reaction has several advantages over existing methods and provides substituted pyrroles in good-to-excellent yields (79,89%). The supramolecular catalysis of the reaction was studied using 1H-NMR spectroscopy. , -Cyclodextrin can be recovered and reused several times without loss of activity. [source] Stereoselective Aldol Reactions Catalyzed by Acyclic Amino Acids in Aqueous MicellesHELVETICA CHIMICA ACTA, Issue 1 2007Dong-Sheng Deng Abstract The catalytic properties of all proteinogenic, acyclic amino acids for direct aldol reaction in H2O, assisted by various surfactants, were investigated. The basic and neutral amino acids were shown to be efficient catalysts, giving rise to good-to-excellent yields of adducts (up to 95%), with moderate-to-good diastereoselectivities (up to 86%), L -arginine being the most-effective catalyst. The syn/anti diastereoisomer ratio could be readily tuned by proper choice of the amino acid used. Also, the range of substrates that underwent the reaction was extended to less-reactive aldehydes carrying electron-donating Br substituents. [source] Synthesis of Substituted , -(Hydroxymethyl)- , -iodoacrylates via MgI2 -Promoted Stereoselective Aldol CouplingHELVETICA CHIMICA ACTA, Issue 9 2004Han-Xun Wei The efficient and highly stereoselective syntheses of a variety of (Z)-configured, substituted , -(hydroxymethyl) - , -iodo-acrylates from prop-2-ynoate and various aldehydes was achieved. The synthetic protocol involves a simple one-pot coupling reaction under mild conditions, promoted by MgI2, which serves both as a Lewis acid and iodine source for a BaylisHillman -type reaction. All adducts were generated in good-to-excellent yields, the (Z)-isomers being formed in high selectivity (>98%). The conversion of methyl prop-2-ynoate into an active ,, -iodo allenolate' intermediate, which then nucleophilically attacks an aldehyde, is proposed as a plausible reaction mechanism. [source] Organocatalytic Direct Asymmetric Mannich Reactions of Hydroxyacetone by (2S,5S)-Pyrrolidine-2,5-dicarboxylic AcidCHINESE JOURNAL OF CHEMISTRY, Issue 10 2008Qing GU Abstract The direct one-pot three-component asymmetric Mannich reactions of hydroxyacetone with anilines and benzaldehydes in the presence of (2S,5S)-pyrrolidine-2,5-dicarboxylic acid afforded syn -1,2-amino alcohols in good-to-excellent yields (64% ,95%) and up to 96% ee. [source] | ||||||||||