A Convenient Synthesis of N-Methoxy-N-Methylamides from Carboxylic Acids
作者:Mukund P. Sibi、Chad C. Stessman、Jeffrey A. Schultz、James W. Christensen、Jianliang Lu、Mali Marvin
DOI:10.1080/00397919508012689
日期:1995.4
Abstract Carboxylic acids can be converted to their corresponding N-methoxy-N-methylamides in high yields using 2-chloro-1-methylpyridinium iodide as the coupling agent. The reaction proceeds without racemization when chiral carboxylic acids are used as the starting material.
straightforward synthesis of acylating reagents such as Weinreb and MAP amides fromaromatic, aliphatic carboxylic acids, and amino acids using PPh3/NBS combination is described. A chemo-selective modification of the carboxylic acid group into Weinreb amide in the presence of more reactive aldehydes and ketones is presented. All reactions were performed at ambient temperature under air using undried commercial
A new type of tridentate chiral spiro aminophosphine−oxazoline ligands (SpiroOAP) have been synthesized through four steps. The SpiroOAP ligands are highly efficient for the asymmetric hydrogenation of α‐keto amides, providing a variety of synthetically useful α‐hydroxy amides with excellent enantioselectivity (up to 98% ee) and turnover numbers (up to 10,000).
Rh(I)-Catalyzed Intermolecular Hydroacylation: Enantioselective Cross-Coupling of Aldehydes and Ketoamides
作者:Kevin G. M. Kou、Diane N. Le、Vy M. Dong
DOI:10.1021/ja504296x
日期:2014.7.2
Under Rh(I) catalysis, alpha-ketoamides undergo intermolecular hydroacylation with aliphatic aldehydes. A newly designed Josiphos ligand enables access to alpha-acyloxyamides with high atom-economy and enantioselectivity. On the basis of mechanistic and kinetic studies, we propose a pathway in which rhodium plays a dual role in activating the aldehyde for cross-coupling. A stereochemical model is provided to rationalize the sense of enantioinduction observed.
.alpha.-Keto Amides and 1,2-Diketones from N,N'-Dimethoxy-N,N'-dimethylethanediamide. A Synthetic and Mechanistic Investigation
作者:Mukund P. Sibi、Mali Marvin、Rajiv Sharma
DOI:10.1021/jo00121a021
日期:1995.8
N,N'-Dimethoxy-N,N'-dimethylethanediamide (1), a 1,2-dicarbonyl synthon prepared from oxalyl chloride, undergoes nucleophilic displacements with Grignard reagents to provide alpha-keto amides 2-12 in 28-90% yields. The synthon also undergoes double nucleophilic displacements with organolithium reagents to furnish symmetrical 1,2-diketones 15-23 in 15-84% yields. A mechanism accounting for all the products from the reaction of 1 with nucleophiles has been proposed. Several control experiments were carried out to support the proposed mechanism.