Home About us Contact
|
Home About us Contact | ||
|
|
||
High Isolated Yields (high + isolated_yield)
Selected AbstractsIridium-Difluorphos-Catalyzed Asymmetric Hydrogenation of 2-Alkyl- and 2-Aryl-Substituted Quinoxalines: A General and Efficient Route into TetrahydroquinoxalinesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Damien Cartigny Abstract A highly efficient and general iridium-difluorphos-catalyzed asymmetric hydrogenation of diverse 2-alkyl- and 2-aryl-substituted quinoxalines into biologically and pharmaceutically relevant 2-substituted-1,2,3,4-tetrahydroquinoxaline units has been developed. High isolated yields and excellent enantioselectivities of up to 95% for 2-alkyl-substituted quinoxalines and of up to 94% for 2-aryl-substituted quinoxalines were obtained. [source] Rearrangement of a (Dithiolato)platinum(II) Complex Formed by Reaction of Cyclic Disulfide 7,8-Dithiabicyclo[4.2.1]nona-2,4-diene with a Platinum(0) Complex: Oxidation of the Rearranged (Dithiolato)platinum(II) ComplexCHEMISTRY - A EUROPEAN JOURNAL, Issue 15 2007Akihiko Ishii Prof. Abstract Reaction of the title bicyclic disulfide 16 with [(Ph3P)2Pt(,2 -C2H4)] (2) yielded the corresponding (dithiolato)platinum(II) complex 17 by oxidative addition. The initial product 17 isomerized at room temperature in a [1,5]-sulfur rearrangement to give another (dithiolato)platinum(II) complex 18 in high isolated yield. Oxidation reactions of 18 with dimethyldioxirane (DMD) provided (sulfenato-thiolato)platinum(II) 23, (sulfinato-thiolato)platinum(II) 24, (sulfenato-sulfinato)platinum(II) 25, and (disulfinato)platinum(II) 26 complexes, the structures of which were elucidated by NMR spectroscopy and X-ray crystallography. The oxidation process took place regioselectively in the first step and chemoselectively in the second. The selectivities are discussed. [source] First Heterogeneous Ligand- and Salt-Free Larock Indole SynthesisADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009Nelly Batail Abstract A new ligand- and salt-free procedure using heterogeneous palladium catalysts for the Larock indole and benzofuran synthesis is reported. After optimisation of the reaction conditions, good to high isolated yields have been achieved for a variety of structures. Recycling studies have shown that the palladium catalysts can be readily recovered and reused. Reactions and recovery of the palladium catalysts can be carried out in the presence of air, without any particular precaution. [source] Enantioselective alkynylation of aldehydes catalyzed by a camphor sulfonylated amino alcohols titanium(IV) catalyst systemAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 5 2010Shaohua Gou Abstract A new titanium(IV) complex has been developed for the effective enantioselective alkynylation of phenylacetylene addition to aldehydes. The titanium(IV) complex was readily prepared in situ from (R)-C-(7,7-dimethyl-2-oxo-bicyclo[2.2.1]hept-1-yl)-(1R,2S)- N -(2-hydroxy-1,2-diphenyl-ethyl)-methanesulfonamide (1h) and tetraisopropyl titanate [Ti(i -OPr)4]. A variety of aromatic aldehydes and ,,,-unsaturated aldehydes were found to be suitable substrates in the presence of the camphor sulfonylated amino alcohol titanium(IV) complex [10 mol% 1h, 40 mol% Ti(i -OPr)4]. The desired propargylic alcohols were afforded with high isolated yields (up to 90%) and moderate enantioselectivities (up to 65% ee) under mild conditions. Copyright © 2010 John Wiley & Sons, Ltd. [source] Asymmetric 1,4-conjugation addition of diethylzinc to cyclic enones catalyzed by a self-assembled copper complexAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 12 2009Shaohua Gou Abstract A new self-assembled catalyst system based on copper complex was developed for the 1,4-conjugation addition of diethyl zinc to cyclic enones. The self-assembled catalyst was readily prepared from (R)-[1,1,]binaphthalenyl-2,2,-diamine (1a), (L)-tryptophan (3f) and copper(I) chloride (CuCl). Several enones were found to be suitable substrates in the presence of the self-assembled copper catalyst [10 mol% (R)-1a, 10 mol% (L)-3f and 10 mol% CuCl] under optimized conditions. The desired products were afforded with high isolated yields (up to 98%) and moderate to good enantioselectivities (up to 80% ee) in mild conditions (at 0 °C). Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||