Aqueous Asymmetric Mukaiyama Aldol Reaction Catalyzed by Chiral Gallium Lewis Acid with Trost-Type Semi-Crown Ligands
作者:Hui-Jing Li、Hong-Yu Tian、Yan-Chao Wu、Yong-Jun Chen、Li Liu、Dong Wang、Chao-Jun Li
DOI:10.1002/adsc.200505089
日期:2005.7
generates highly effective chiral gallium Lewis acid catalysts for aqueous asymmetric aldolreactions of aromatic silyl enol ethers with aldehydes. A ligand-acceleration effect was observed. Water is essential for obtaining high diastereoselectivity and enantioselectivity. The p-phenyl substituent in aromatic silyl enol ether (2 h) plays an important role and increases the enantioselectivity up to 95%
Lewis Acid-Promoted Cross Aldol Reaction of Aldehydes with Ketones Utilizing 3-Methyl-2-phenyl-2-(2-oxoalkyl)benzothiazolines as an Enolate-Transferring Reagent
The treatment of a variety of 3-methyl-2-phenyl-2-(2-oxoalkyl)benzothiazolines with aldehydes in the presence of 2 equivalents of SnCl4 in dichloromethane at −78°C underwent a carbon–carbon bond cleavage at the 2-position of the benzothiazoline ring releasing an 2-oxoalkyl moiety followed by the concurrent aldol-type reaction with aldehydes to afford the corresponding β-hydroxy ketones. Among the Lewis acids examined, SnCl4 was found to be most effective, while a similar reaction employing trimethylsilyl trifluoromethanesulfonate as an electrophilic promoter mainly gave the corresponding aldol-condensation product. In the case of the reaction with 3-methyl-2-phenyl-2-(1-substituted 2-oxoalkyl)benzothiazolines, a diastereomeric mixture of α-substituted β-hydroxy ketones as cross aldol products was obtained and the anti preference was generally observed for reactions with the benzothiazolines possessing an aromatic ketone moiety in modest to poor selectivity ranging between 69:31 and 57:43. In contrast to this, the reaction of the benzothiazoline possessing an alkyl ketone moiety, 3-methyl-2-phenyl-2-(1-methyl-2-oxobutyl)benzothiazoline, with benzaldehyde showed syn preference in modest selectivity of 70:30.
Ruthenium-Catalyzed Tandem Olefin Migration/Aldol and Mannich-Type Reactions in Water and Protic Solvents
作者:Mingwen Wang、Xiao-Fan Yang、Chao-Jun Li
DOI:10.1002/ejoc.200390155
日期:2003.3
[RuCl2(PPh3)3] has been developed, through a tandemolefinmigration/aldolreaction in a water/toluene mixture. The presence of In(OAc)3 promoted the aldolreaction with α-vinylbenzyl alcohol (4) and aldehyde, while treatment of 3-buten-2-ol (2) with imines generated Mannich-typereaction products; syn isomers were formed as the major diastereomers for the aldol products 3a−3g and 5a−5e and the Mannich
ENANTIOSELECTIVE CROSS ALDOL REACTION VIA DIVALENT TIN ENOLATE
作者:Nobuharu Iwasawa、Teruaki Mukaiyama
DOI:10.1246/cl.1982.1441
日期:1982.9.5
Highly enantioselective cross aldolreaction between aromatic ketones and various aldehydes is achieved via divalent tinenolates employing chiral diamines derived from (S)-proline as ligands.
Self-Assembled Single-Walled Metal-Helical Nanotube (<b>M-HN</b>): Creation of Efficient Supramolecular Catalysts for Asymmetric Reaction
作者:Jian Jiang、Yan Meng、Li Zhang、Minghua Liu
DOI:10.1021/jacs.6b08808
日期:2016.12.7
variety of single-walled M-HN catalysts could be fabricated, in which the coordination sites could serve as the catalytic sites. On the other hand, using a slight amount of these catalysts, significant reactivity and enantioselectivity were realized for certain asymmetric reactions under mild conditions. Remarkably, Bi(III)-HN could catalyze the asymmetric Mukaiyamaaldolreaction with high enantioselectivity