Microwave Assisted Amidation of 5-Aminoisophtalic Acid Dimethyl Ester Catalyzed by Imidazolium Ionic Liquids

Amide functionalities present in living system as peptides and possess various biological role. Many synthetic amides also possess biological activities due to the possibility of interaction with cellular liquids such as those compounds useful as a contrast agent in radiographic method. Synthesis of amides from the carboxylic acid or derivatives normally require heating and catalyst. In this report, an environmentally benign synthesis of amide was carried out utilizing microwave radiation and catalyzed by imidazolium ionic liquids (BMIMCl). Microwave radiation provided efficient heating through activation of chemical bonds instead of conventional conductivity methods hence increasing the rate of reactions. Ionic liquids were suitable material in this synthesis due to non-volatile nature as well as stability under high temperature and microwave heating. Furthermore, ionic liquids are tunable material that can be designed for the specific synthesis and functioned as a catalyst. The optimum condition for coupling of 5-Amino-isophthalic acid dimethyl ester with an amino diol was found at 80 °C, 90 minutes, under radiation of microwave at the power of 300 Watt. The product was obtained at 38.46% yield. Furthermore, the methodology was applied to synthesis radiographic material and was successful to obtain product with 48.78% yield. The products were characterized by NMR spectroscopy.

Flexible Entry into 3-Arylpent-2-enedioic Acids via Heck–Matsuda Arylation of Dimethyl Glutaconate with Arenediazonium Tosylates

For the preparation of compound libraries of Michael acceptors with tunable reactivity toward nuclophilic selenocysteine residue of thioredoxin reductase, a range of 3-arylglutaconic acids were required. The existing methods at the time had limited scope or involved several steps. A hitherto undescribed protocol for direct palladium(II) acetate-catalyzed arylation of glutaconic acid dimethyl ester at position 3 has been developed with a diverse set of arenediazonium tosylates followed by hydrolysis. This generally good-yielding two-step sequence displayed a propensity to deliver E-configured coupling products while compounds mostly featured in the literature were predominantly Z-configured. The possibility for preparing a library of 4-arylpyridine-2,6(1H,3H)-diones has been exemplified.

Crystal structures of hibiscus acid and hibiscus acid dimethyl ester isolated fromHibiscus sabdariffa(Malvaceae)

The biologically active title compounds have been isolated fromHibiscus sabdariffaplants, hibiscus acid as a dimethyl sulfoxide monosolvate [systematic name: (2S,3R)-3-hydroxy-5-oxo-2,3,4,5-tetrahydrofuran-2,3-dicarboxylic acid dimethyl sulfoxide monosolvate], C6H6O7·C2H6OS, (I), and hibiscus acid dimethyl ester [systematic name: dimethyl (2S,3R)-3-hydroxy-5-oxo-2,3,4,5-tetrahydrofuran-2,3-dicarboxylate], C8H10O7, (II). Compound (I) forms a layered structure with alternating layers of lactone and solvent molecules, that include a two-dimensional hydrogen-bonding construct. Compound (II) has two crystallographically independent and conformationally similar molecules per asymmetric unit and forms a one-dimensional hydrogen-bonding construct. The known absolute configuration for both compounds has been confirmed.