Catalytic, Enantioselective α-Additions of Isocyanides: Lewis Base Catalyzed Passerini-Type Reactions
作者:Scott E. Denmark、Yu Fan
DOI:10.1021/jo050549m
日期:2005.11.1
(Passerini-type reactions). The catalytic system of silicontetrachloride and a chiral bisphosphoramide (R,R)-1b provided high yields and good to excellent enantioselectivities for the addition of tert-butyl isocyanide to a wide range of aldehydes (aromatic, heteroaromatic, olefinic, acetylenic, aliphatic). Aqueous workup afforded the α-hydroxy tert-butyl amides whereas a low-temperature methanol quench followed
Resolution of (±)-mandelic- and (±)-2-(chlorophenoxy)propionic- acid derivatives by crystallization of their diastereomeric amides with (R)- or (S)-α-arylethylamines
An alternative and cost effective route for the resolution in high ees (95–99%) of (±)-mandelic- and (±)-2-(chlorophenoxy)propionic- acid derivatives is reported. The key step involves the covalent derivatization and separation of their diastereomeric amides with (R)- or (S)-α-arylethylamines.
Asymmetric Catalytic Hydrogenations of Chiral α-Keto Amides
作者:Kaoru Harada、Toratane Munegumi
DOI:10.1246/bcsj.57.3203
日期:1984.11
Asymmetric catalytic hydrogenations of chiralpyruvamides were carried out using palladium on charcoal (Pd-C) as a catalyst to give lactamides with the diastereoisomeric purities (d.p.) of up to 62%. It was found that there was a linear correlation between the d.p. and the dielectric constant of the solvents used in the hydrogenations of chiralpyruvamides. The results were explained by employing the
Enantiopurification of Mandelic Acid by Crystallization-Induced Diastereomer Transformation: An Experimental and Computational Study
作者:Tharit Lerdwiriyanupap、Ruel Cedeno、Phattananawee Nalaoh、Sareeya Bureekaew、Vinich Promarak、Adrian E. Flood
DOI:10.1021/acs.cgd.2c01551
日期:2023.3.1
(CIDT) was achieved enabling good product yield (>70%) and excellent optical purity (>92%). Enantiopure mandelicacid (∼91% e.e.) can then be recovered via acid hydrolysis. This work highlights that for compounds that are neither conveniently racemizable nor conglomerate-forming such as mandelicacid, CIDT is a powerful alternative to the deracemization technique, capable of yields greater than the 50%