RESUMEN
Chiral sulfoximines have recently been considered as promising bioisosteres in medicinal chemistry. However, methods for preparing chiral sulfoximines in a stereoselective manner are underdeveloped. Herein, we demonstrate an asymmetric synthesis of chiral sulfoximines through a stereospecific S-alkylation of readily accessible chiral sulfinamides under practical conditions. A key to establishing the practical conditions was the identification of the intermediate structure in our previously reported S-alkylation by X-ray crystallographic analysis.
Asunto(s)
Química Farmacéutica , Azufre , Alquilación , Estructura Molecular , EstereoisomerismoRESUMEN
Optically active sulfoximines are a promising substance in medicinal chemistry. However, a methodology for preparing chiral sulfoximines in a stereoselective manner has been underdeveloped. Here, we report an asymmetric synthesis of chiral sulfoximines having an aryl group by the newly developed sulfur-selective arylation of easily accessible chiral sulfinamides. The utility of the present method is demonstrated by the asymmetric synthesis of a key intermediate of a COX-2 inhibitor.
RESUMEN
Cyclic sulfoximines were readily synthesized by the cyclization of N-propargylsulfinamides without using expensive and toxic metal catalysts. This cyclization proceeded without loss of optical purity of chiral sulfinamides through the unusual sulfur-carbon bond formation promoted by an inexpensive inorganic base. This stereospecific cyclization offers a general approach to the asymmetric synthesis of chiral cyclic sulfoximines as an emerging heterocycle in medicinal chemistry.
RESUMEN
Innovation in drug discovery critically depends on the development of new bioisosteric groups. Chiral sulfoximines, which contain a tetrasubstituted sulfur atom that bears one nitrogen, one oxygen, and two different carbon substituents, represent an emerging chiral bioisostere in medicinal chemistry. Chiral sulfoximines are conventionally prepared by a stereospecific nitrene transfer reaction to chiral sulfoxides; however, the number of readily available chiral sulfoxides remains limited. Herein, we report the asymmetric synthesis of a class of hitherto difficult-to-access chiral sulfoximines with two structurally similar alkyl chains. Our synthetic approach is based on the sulfur-selective alkylation of easily accessible chiral sulfinamides with commercially available reagents under simple and safe conditions. This stereospecific S-alkylation offers a general and scalable approach to the asymmetric synthesis of chiral sulfoximines, which represent important substructures in bioactive molecules.
Asunto(s)
Amidas/química , Iminas/química , Sulfóxidos/síntesis química , Alquilación , Catálisis , Estructura Molecular , Solventes/química , Estereoisomerismo , Temperatura , Factores de TiempoRESUMEN
We report a dynamic kinetic resolution (DKR) of chiral 4-pentenals by olefin hydroacylation. A primary amine racemizes the aldehyde substrate via enamine formation and hydrolysis. Then, a cationic rhodium catalyst promotes hydroacylation to generate α,γ-disubstituted cyclopentanones with high enantio- and diastereoselectivities.
Asunto(s)
Aldehídos/química , Alquenos/química , Ciclopentanos/síntesis química , Termodinámica , Acilación , Catálisis , Ciclopentanos/química , Hidrólisis , Cinética , Estructura Molecular , Rodio/química , EstereoisomerismoRESUMEN
2-O-α-d-Glucopyranosyl-l-ascorbic acid (AA-2G) is one of the stable ascorbic acid (AA) derivatives known as provitamin C agents. We have previously synthesized two types of monoacylated derivatives of AA-2G, 6-O-acyl-2-O-α-d-glucopyranosyl-l-ascorbic acids having a straight-acyl chain of varying length from C4 to C18 (6-sAcyl-AA-2G) and a branched-acyl chain of varying length from C6 to C16 (6-bAcyl-AA-2G) in order to improve the bioavailability of AA-2G. In this study, 6-sAcyl-AA-2G and 6-bAcyl-AA-2G per se showed the inhibitory effects on hyaluronidase activity and degranulation. 6-sAcyl-AA-2G exhibited strong inhibitory effects on hyaluronidase activity and degranulation in a concentration-dependent manner, and the inhibitory effects tended to become stronger with increasing length of the acyl chain. 2-O-α-d-Glucopyranosyl-6-O-hexadecanoyl-l-ascorbic acid (6-sPalm-AA-2G), which has a straight C16 acyl chain, was the most potent effective for inhibition of hyaluronidase activity and for inhibition of degranulation among the 6-sAcyl-AA-2G derivatives and the two isomers of 6-sPalm-AA-2G. Furthermore, percutaneous administration of 6-sPalm-AA-2G significantly inhibited IgE-mediated passive cutaneous anaphylaxis reaction in mice. These findings suggest that 6-sPalm-AA-2G will be useful for treatment of allergies.
Asunto(s)
Antialérgicos/química , Antialérgicos/farmacología , Ácido Ascórbico/análogos & derivados , Hialuronoglucosaminidasa/antagonistas & inhibidores , Animales , Antialérgicos/administración & dosificación , Ácido Ascórbico/administración & dosificación , Ácido Ascórbico/química , Ácido Ascórbico/farmacología , Degranulación de la Célula , Línea Celular , Humanos , Hipersensibilidad/tratamiento farmacológico , Masculino , Ratones Endogámicos ICR , Azúcares Ácidos/química , Azúcares Ácidos/farmacologíaRESUMEN
A highly stereoselective synthesis of hitherto less accessible chiral α-tertiary amines with multiple structurally similar linear carbon chains was achieved through chiral auxiliary mediated addition of organolithium reagents to the geometrically well-controlled alkynyl Z-ketimines. This stereoselective nucleophilic addition offers a general approach to the asymmetric synthesis of nitrogen-containing chiral materials.
RESUMEN
α-Functionalization of ketones in an umpolung fashion can be achieved by nucleophilic addition to the oxy-allyl cation intermediate. However, applicable carbon nucleophiles are limited to ones with high nucleophilicity. Additionally, introduction of a leaving group to the α-position of ketone substrates is required beforehand. Herein, we report the CuCl2 -mediated oxidative intramolecular α-arylation of ketones with less nucleophilic phenolic moieties as carbon nucleophiles via α-chlorination of ketones and the subsequent generation of the oxy-allyl cation intermediates, giving ketones with a quaternary carbon center at the α-position.
RESUMEN
In the presence of a Brønsted acid catalyst, both aldehydes and N-Boc-aminals were converted to enecarbamates and N-Boc-iminium salts as activated nucleophiles and electrophiles, respectively, giving unprecedented Mannich adducts. The asymmetric variant of the present Mannich reaction has also been demonstrated with a chiral phosphoric acid catalyst.