RESUMEN
A highly efficient and simple method for the synthesis of 2-alkylbenzothiazoles through the condensation of 2-aminothiophenol and aliphatic aldehydes in the presence of active carbon/silica gel is described. The reaction proceeded under solvent-free and microwave irradiation to afford 2-alkylbenzothiazoles in high yields. This method was extended to the synthesis of bile acid derivatives containing a benzothiazole ring and obtained the desired products in high yields. The anti-inflammatory activity and cytotoxicity of the newly synthesized benzothiazole derivatives of bile acid were tested; the results showed that anti-inflammatory activities of all tested compounds tested were higher than that of standard drugs, such as indomethacin.
Asunto(s)
Aldehídos/química , Compuestos de Anilina/química , Ácidos y Sales Biliares/síntesis química , Carbón Orgánico/química , Ácidos Grasos/química , Microondas , Gel de Sílice/química , Tiadiazoles/síntesis química , Animales , Antiinflamatorios , Ácidos y Sales Biliares/química , Ácidos y Sales Biliares/farmacología , Femenino , Ratones Endogámicos ICR , Fenómenos Químicos Orgánicos , Solventes , Tiadiazoles/química , Tiadiazoles/farmacologíaRESUMEN
Mild and regioselective conversion of 3-keto-5α- and 3-keto-5ß-steroids (trans A/B- and cis A/B-ring juncture, respectively) to the corresponding enones (Δ(1)- and Δ(4)-3-ketones) by treatment with o-iodoxybenzoic acid (IBX) catalyzed by trifluoroacetic acid (TFA) in DMSO, is described. The IBX-mediated reaction involved dehydrogenation of the α- and ß-hydrogen atoms of the 3-ketones to give the enones regioselectively in good isolated yields without concomitant formation of related dienones and trienones.
Asunto(s)
Yodobencenos/química , Cetonas/química , Cetosteroides/química , Ácido Trifluoroacético/química , Dimetilsulfóxido/química , Cetonas/síntesis química , EstereoisomerismoRESUMEN
In the synthesis of dipeptides (Boc-AA(1)-AA(2)-OPac: AA(1) and AA(2) represent amino acids) protected by phenacyl (Pac) ester, amines and solid bases as the base for the conversion of the trifluoroacetic acid (TFA) salt of the amino component (TFA·H-AA(2)-OPac) into the corresponding free amino component (H-AA(2)-OPac) were examined. The synthesis of a dipeptide (Boc-Ala-Gly-OPac) using amines for the conversion afforded an unsatisfactory yield with by-products. On the other hand, the use of neutral alumina-supported Na(2) CO(3) (Na(2)CO(3) /n-Al(2)O(3)) as a solid base for the conversion provided the dipeptide in a quantitative yield without by-products. The application of Na(2)CO(3) /n-Al2 O3 to the synthesis of some dipeptides protected by Pac ester gave the desired peptides in excellent yields.
Asunto(s)
Carbonatos/química , Dipéptidos/síntesis química , Ésteres/síntesis química , Óxido de Aluminio/química , Dipéptidos/química , Ésteres/química , Concentración de Iones de Hidrógeno , Espectroscopía de Resonancia MagnéticaRESUMEN
Simple and efficient cross coupling of alcohols was developed in the presence of NaHSO4/SiO2 to give the corresponding substituted olefins. Direct coupling of alcohols and alkenes was also achieved to give substituted olefins. NaHSO4/SiO2 could be recycled 7 times without loss of catalytic activity.