128899-83-2Relevant articles and documents
Synthesis of Enantiomerically Pure β-Hydroxy Ketones via β-Keto Weinreb Amides by a Condensation/Asymmetric-Hydrogenation/Acylation Sequence
Diehl, Julian,Brückner, Reinhard
supporting information, p. 278 - 286 (2017/01/24)
An established route to enantiomerically pure β-hydroxy ketones proceeds through the asymmetric hydrogenation of β-keto esters, an ester/amide exchange, and the use of the resulting β-hydroxy amide for the acylation of an organometallic compound. We shortened this route by showing that β-keto Weinreb amides are hydrogenated with up to 99 % ee in the presence of [Me2NH2]+{[RuCl(S)-BINAP]2(μ-Cl)3}–(0.5 mol-%) at room temp./5 bar. These Weinreb amides were prepared by seemingly obvious yet unprecedented condensations of lithiated N-methoxy-N-methylacetamide with carboxylic chlorides (51–87 % yield). The resulting β-hydroxy Weinreb amides were used for the acylation of organolithium and Grignard reagents. They thus gave enantiomerically pure β-hydroxy ketones (28 examples). A selection of these compounds gave anti-1,3-diols after another C=O bond hydrogenation, or syn-1,3-diols by a Narasaka–Prasad reduction.
The zirconium alkoxide-catalyzed aldol-tishchenko reaction of ketone aldols
Schneider, Christoph,Hansch, Markus,Weide, Timo
, p. 3010 - 3021 (2007/10/03)
The aldol-Tishchenko reaction of ketone aldols as enol equivalents has been developed as an efficient strategy to furnish differentiated 1,3-anti-diol monoesters in one step. The thermodynamically unstable ketone aldols undergo a facile retro-aldolization to yield a presumed zirconium enolate in situ, which then undergoes the aldol-Tishchenko reaction in typically high yields and with complete 1,3-anti diastereocontrol. Evaluation of a broad range of metal alkoxides as catalysts and optimization of the reaction protocol led to a modified zirconium alkoxide catalyst with attenuated Lewis acidity and dichloromethane as solvent, which resulted in suppression of the undesired acyl migration to a large extent. Various ketone aldols have been prepared and subjected to the general process, giving rise to a broad range of differently substituted 1,3-anti-diol monoesters, which may be hydrolyzed to the corresponding 1,3-anti-diols.
Chiral 1,2-bis(phosphetano)benzenes: Preparation and use in the Ru- catalyzed hydrogenations of carbonyl derivatives
Marinetti, Angela,Genet, Jean-Pierre,Jus, Sebastien,Blanc, Delphine,Ratovelomanana-Vidal, Virginie
, p. 1160 - 1165 (2007/10/03)
Chiral 1,2-bis(phosphetano)benzenes are readily prepared from accessible, optically pure 1,3-diol cyclic sulfates. Their ruthenium complexes catalyze the enantioselective hydrogenations of functionalized carbonyls with moderate-to-high enantiomeric excesses. High levels of diastereo- and enantioselectivity are achieved, especially in the hydrogenation of β-diketones to the corresponding anti-1,3-diols.
