Thioamide-Substituted Cinchona Alkaloids as Efficient Organocatalysts for Asymmetric Decarboxylative Reactions of MAHOs

Organocatalytic enantioselective decarboxylative protonation of α-alkyl-α-aryl malonate monoesters

In contrast to the well-established enzymatic enantioselective decarboxylative protonation (EDP), the corresponding chemocatalytic reactions of acyclic malonic acid derivatives remain challenging. Herein, we developed a biomimetic EDP of α-alkyl-α-aryl malonate monoesters using a chiral 1,2-trans-diaminocyclohexane-based N-sulfonamide as an organocatalyst. The method demonstrates excellent chemical yields, good enantioselectivity, mild reaction conditions, and the generation of only CO2 as waste.

Synthesis and Reactivity of Fluorinated Dithiocarboxylates to Prepare Thioamides-Effective Access to a 4-Styrenylthioamide-Cinchona Alkaloid Monomer

A simple and rapid access to fluorinated dithioesters was developed by a one-pot sequence corresponding to a Grignard reaction-Mitsunobu type substitution. These activated dithioesters have shown excellent reactivity in an aminolysis reaction from simple or more complex primary amines such as cinchona alkaloids. A stoichiometric amount of amine was sufficient to prepare various thioamides, including a 4-styrenylthioamide cinchonidine monomer, under environmentally friendly conditions, at room temperature, and in a very short time.

Synthesis of the Kinase Inhibitors Nintedanib, Hesperadin, and Their Analogues Using the Eschenmoser Coupling Reaction

A novel synthetic approach involving an Eschenmoser coupling reaction of substituted 3-bromooxindoles (H, 6-Cl, 6-COOMe, 5-NO₂) with two substituted thiobenzanilides in dimethylformamide or acetonitrile was used for the synthesis of eight kinase inhibitors including Nintedanib and Hesperadin in yields exceeding 76%. Starting compounds for the synthesis are also easily available in good yields. 3-Bromooxindoles were prepared either from corresponding isatins using a three-step synthesis in an average overall yield of 65% or by direct bromination of oxindoles (yield of 65-86%). Starting N-(4-piperidin-1-ylmethyl-phenyl)-thiobenzamide was prepared by thionation of the corresponding benzanilide in an 86% yield and N-methyl-N-(4-thiobenzoylaminophenyl)-2-(4-methylpiperazin-1-yl)acetamide was prepared by thioacylation of the corresponding aniline with methyl dithiobenzoate in an 86% yield.

Enantioselective decarboxylative protonation and deuteration of β-ketocarboxylic acids

Enantioselective decarboxylative protonation of tetralone-derived β-ketocarboxylic acids was achieved with up to 89% enantiomeric excess (ee)-in the presence of a chiral primary amine catalyst. Furthermore, this method was applied to enantioselective deuteration to afford the corresponding α-deuterioketones with up to 88% ee.

Decarboxylative Mannich Reactions with Substituted Malonic Acid Half-Oxyesters

The decarboxylative Mannich reaction between imines and substituted malonic acids half-oxyesters (SMAHOs) has been developed using 1,4-diazabicyclo[2.2.2]octane (DABCO) as an organocatalyst. The reaction proceeds under simple reaction conditions and tolerates a broad range of substrates, affording general access to β^2,3-aminoesters, the syn diastereomer being the major one. An alternative multicomponent protocol has also been developed to increase the overall eco-compatibility of the process.

Catalytic enantioselective decarboxylative nucleophilic addition reactions using chiral organocatalysts

Catalytic decarboxylative reactions are attractive as biomimetic and environmentally friendly reaction processes. This review summarizes the recent results of organocatalytic enantioselective decarboxylative reactions of malonic acid half oxy- or thioesters, β-ketoacids, and related compounds from October 2013 to December 2019.

A highly effective and mild protocol for the production of 1-thioamidoalkyl-2-naphthols using 1,3-disulfonic acid imidazolium trifluoroacetate as a dual-functional catalyst

A solvent-free protocol for the production of 1-thioamidoalkyl-2-naphthols via a one-pot multi-component reaction of arylaldehydes with 2-naphthol and thioacetamide using the ionic liquid 1,3-disulfonic acid imidazolium trifluoroacetate ([Dsim][TFA]) is described. Furthermore, a plausible and attractive mechanism based on the dual functionality of the catalyst is proposed. Because of the dual functionality of [Dsim][TFA] (possessing acidic and basic sites), it is found to be generally highly effective, affording the products in high yields and short reaction times under mild conditions. We claim that this is one of the best protocols for the synthesis of 1-thioamidoalkyl-2-naphthols (in terms of yield, temperature, conditions, and/or the reaction time).