Asymmetric Hydrogenation of Aromatic Ketones Catalyzed by the TolBINAP/DMAPEN−Ruthenium(II) Complex: A Significant Effect of <i>N</i>-Substituents of Chiral 1,2-Diamine Ligands on Enantioselectivity
mode of enantioface selection was interpreted by using transition state models based on the X-ray structure of the catalyst precursor. The chiral catalyst effected the hydrogenation of alkyl aryl ketones and arylglyoxal dialkyl acetals to afford the chiral alcohol in >99% ee in the best cases. Hydrogenation of racemic benzoin methyl ether with the chiral catalyst through dynamic kinetic resolution gave
Synergistic Catalysis of Se and Cu for the Activation of
<scp>
<i>α</i>
‐H
</scp>
of Methyl Ketones with Molecular Oxygen/Alcohol to Produce
<scp>
<i>α</i>
‐Keto
</scp>
Acetals
<sup>†</sup>
Selenium and copper synergistically catalyzed the oxidation/alkoxylation of methyl ketones to synthesize α‐keto acetals directly. Using O2 as oxidant and alcohol as solvent and alkoxylation reagent, the reaction is practical from industrial viewpoint. Mechanistic studies revealed that copper promoted the oxidation of organoselenium intermediates with O2 to allow the key rearrangement and selenoxide
A catalyst system consisting of RuCl2[(S)-tolbinap][(R)-dmapen] and t-C4H9OK in 2-propanol effects asymmetric hydrogenation of arylglyoxal dialkylacetals to give the alpha-hydroxy acetals in up to 98% ee. Hydrogenation of racemic alpha-amidopropiophenones under dynamic kinetic resolution predominantly gives the syn alcohols in up to 99% ee and > 98% de, while the reaction of racemic bezoin methyl ether gives the anti alcohols in excellent stereoselectivity.
One-pot synthesis of α-ketoacetals from aryl methyl ketones in the presence of selenous acid catalyzed by boron trifluoride etherate
作者:Icydora Kharkongor、Bekington Myrboh
DOI:10.1016/j.tetlet.2015.05.087
日期:2015.7
A simple and efficient one-pot preparation of α-ketoacetals from substituted acetophenones and triethylorthoformate in the presence of H2SeO3 and BF3·Et2O as catalyst has been developed. The desired products are obtained in good yields by a simple protocol involving neat and mild reaction conditions. The present methodology provides an attractive alternative method for the preparation of α-ketoacetal
开发了一种简单有效的一锅法,在H 2 SeO 3和BF 3 ·Et 2 O作为催化剂的情况下,由取代的苯乙酮和原甲酸三乙酯制备α-酮缩醛。通过涉及纯净的和温和的反应条件的简单方案以高收率获得所需产物。本方法提供了制备α-酮缩醛衍生物的有吸引力的替代方法。
Direct asymmetric reductive amination of α-keto acetals: a platform for synthesizing diverse α-functionalized amines
efficient and straightforward method to synthesize enantio-enriched N-unprotected α-amino acetals via ruthenium-catalyzed direct asymmetric reductive amination. The α-amino acetal products are versatile and valuable platform molecules that can be converted to the corresponding α-amino acids, amino alcohols, and other derivatives by convenient transformations.