l-Amino Acid Based Urea–Tertiary Amine-Catalyzed Chemoselective and Asymmetric Stereoablative Carboxylation of 3-Bromooxindoles with Malonic Acid Half Thioesters

Abstract

An L-amino acid based urea-tertiary amine-catalyzed enantioselective stereoablative carboxylation of 3-bromooxindoles with malonic acid half thioesters (MAHTs) and diverse commercially available carboxylic acids has been developed. A series of valuable 3-substituted 3-hydroxy-2-oxindoles were obtained in high enantioselectivities (up to 93% ee). This chemoselective reaction represents the first example of MAHTs as carboxylating agents.

Formation of Ternary Inclusion Crystal and Enantioseparation of Alkyl Aryl Sulfoxides by the Salt of Urea-Modified l-Phenylalanine and an Achiral Amine

“…During the attempt to develop chiral supramolecular host systems from inexpensive natural amino acids, chiral carboxylic acids with a urea moiety were studied for inclusion of hydrogen bond acceptors. Urea moieties are known as strong hydrogen bond donors and have been used as asymmetric organocatalysts, − host molecules, − etc. In this study, enantioselective inclusion of alkyl aryl sulfoxides was attempted with a chiral supramolecular host consisting of an achiral primary amine and a urea-modified chiral carboxylic acid derived from l -amino acids.…”

Asymmetric Catalytic Insertion of α-Diazo Carbonyl Compounds into O–H Bonds of Carboxylic Acids

“…Transition-metal-catalyzed asymmetric insertion of α-diazo compounds into O–H bond donors, such as alcohols, phenols, H 2 O, and carboxylic acids is highly selective and synthetically useful for the synthesis of α-alkoxy, α-aryloxy, α-hydroxyl, or α-acyloxy carbonyl derivatives, respectively . Chiral α-acyloxy carbonyl compounds were usually synthesized from chiral α-hydroxy carbonyl compounds, which, for example, can be obtained from copper- or iron-catalyzed O–H insertion of H 2 O with α-diazocarbonyl compounds in excellent enantioselectivities. , Additionally, asymmetric Passerini reaction and carboxylation reaction could provide access to α-acyloxy carbonyl compounds. The O–H insertion of carboxylic acids with α-diazocarbonyl compounds provides a direct and convenient alternative for the α-acyloxy carbonyl compounds synthesis.…”

Modular Urea‐Based Catalytic Platforms Bearing Flexible Pyridylmethylamine and Rigid Pyridyl‐Imidazolidine Fragments

“…In the main catalytic platforms developed to date (Figure ), urea has been combined with cyclohexanediamine, diphenylethylenediamine, binaphthylamine and cinchona derivatives. Such catalytic platforms have been used in a wide range of asymmetric organocatalysed transformations, including (hetero)‐Michael additions, Huisgen cycloadditions, the reduction of ketones, the alkylation of heterocycles, Horner–Wadsworth–Emmons, aza‐Henry, Mannich and Conia‐ene reactions as well as in kinetic resolutions , …”