New steroid dimer derived from cholic acid as receptor for lanthanum(III) and calcium(II) nitrates

Paryzek, Z.; Piasecka, Monika; Joachimiak, Roman; Luks, Emilia; Radecka‐Paryzek, Wanda

doi:10.1016/s1002-0721(10)60385-7

Cited by 4 publications

(2 citation statements)

References 32 publications

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“…Hydrotalcite catalysts have also been used for other transesterification reactions. − The disadvantages of many of these catalysts include low reusability, long reaction times, the need for more than one solvent, and high energy consumption due to high reaction temperatures duing GLC synthesis. Ca and La mixed-metal oxides not only have higher chemical stability than the single-metal oxides, but also exhibit higher contents of acidic and basic sites, which is essential for the transesterification reaction. − A few authors have studied Ca and La mixed-oxide (CaLa) catalysts and investigated them for different reactions (Table S1, Supporting Information) such as the transesterification of natural oils for biodiesel synthesis and the etherification of glycerol to diglycerol. − Table S1 (Supporting Information) provides a comparative assessment of CaLa catalysts and their applications.…”

Section: Introductionmentioning

confidence: 99%

Glycerol Carbonate Synthesis by Hierarchically Structured Catalysts: Catalytic Activity and Characterization

Kumar

Srivastava

Gläser

et al. 2015

Ind. Eng. Chem. Res.

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The surge in biodiesel production in recent years has resulted in enhanced research interest in the conversion of glycerol to other valuable chemicals such as glycerol carbonate (GLC). In the present study, the catalytic transesterification of glycerol with dimethyl carbonate (DMC) for the production of GLC was studied with calcium–lanthanum mixed-oxide catalysts at different Ca/La molar ratios. These catalysts were synthesized using an exo- and endotemplating method. The physicochemical characteristics of the catalysts were determined using powder X-ray diffraction (XRD), N2 sorption, scanning electron microscopy (SEM), and temperature-programmed desorption (TPD) of CO2 and NH3. The transesterification of glycerol was found to be highly dependent on the basicity of the catalysts. The catalyst with a Ca/La molar ratio of 3 (3CaLa) showed the highest glycerol conversion and GLC yield. Optimization of the reaction parameters and reusability of the catalyst were studied with the 3CaLa catalyst in terms of glycerol conversion, GLC yield, and turnover frequency (TOF). At the optimum operating conditions, namely, a reaction time of 90 min, a DMC/glycerol molar ratio of 5, a catalyst mass of 0.217 g, and a temperature of 90 °C, the glycerol conversion and GLC yield were found to be 94% and 74%, respectively, with a reaction rate of ∼0.14 mol L–1 h–1 (with respect to glycerol).

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Section: Introductionmentioning

confidence: 99%

Glycerol Carbonate Synthesis by Hierarchically Structured Catalysts: Catalytic Activity and Characterization

Kumar

Srivastava

Gläser

et al. 2015

Ind. Eng. Chem. Res.

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“…14 The synthetic approach es reported so far, have led to the preparation of cyclic and acyclic steroidal dimers, by connection between two cyclopentano-perhydrophe nanthrene skeletons (through A-A, B-B, C-C, D-D or A-D rings). [3][4][5] The steroidal moieties could be directly linked, [15][16][17] linked through spacer groups [18][19][20][21][22][23][24][25] and by connection through the steroidal side chains. [26][27][28][29] Concerning steroidal D-D ring dimers linked through spacer groups, a number of pollutant multi-step and low-yielding synthetic approaches have been frequently used.…”

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confidence: 99%

A new facile synthesis of steroid dimers containing 17,17′-dicarboxamide spacers

Carrilho

Pereira

Moreno

et al. 2013

Tetrahedron Letters

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a b s t r a c tA set of new steroid dimers linked through ring D-ring D were synthesized via catalytic diaminocarbonylation of 17-iodo-5 a-androst-16-ene, in the presence of palladium-phosphine in situ catalysts and aliphatic or aromatic diamines as N-nucleophiles. The dimeric steroidal comp ounds containing 17,17 0 -dicarboxamide spacers were obtained through highly chemoselective reactions in good isolated yields and completely characterized by spectro scopic techniques.Ó 2013 Elsevier Ltd. All rights reserved.Steroids are widely found in both plant and animal kingdoms, and play crucial roles in biological systems.1,2 Among them, dimeric steroids constitute a class of compound s, which have recently attracted much attention due to their remarkable properties as potential cytotoxic, antimalarial, anticancer, and cholesterol lowering drugs as well as molecular umbrellas in drug delivery. [3][4][5][6][7][8][9] In addition to their pharmacologic al importance, several dimeric and oligomeric steroids display micellar activity, 10 they can also act as ligands for proteins and trigger cellular processes or may promote the affinity of ligands to their binding locations by providing extra anchoring points to the active site of certain domains. 11,12 Some of the dimers show liquid-crystal behaviour 13 and play key roles in rate enhancem ent from hydrophobic binding. 3 Thus, other environmentall y sustainab le alternativ es to promote steroid dimerizatio ns still constitute a great challenge. It is well established that transition-m etal-catalyzed reactions are versatile tools to introduce different functionalities into specific positions of the steroidal framework, which can render marked changes in their biologica l properties. 30 Recently, our groups have reported several examples on the aminocarbonylation of steroidal alkenyl-iodide s toward carboxamides . 31 Nevertheless, to the best of our knowledge, there is only one example on the synthesis of dimeric steroids involving Pd-catalyzed carbonylativ e dimerization of alkenyl-iodide intermediates , to form 17-carbox ylic anhydrides, in the presence of carbon monoxide and water. 32 It should be also noted that the application of diamines as N-nucleop hiles in palladium-cata lyzed aminocar bonylation toward dicarboxamide s is unprecedented. Therefore, the iodoalkene-based catalytic synthetic strategy described herein provides a complete ly new, facile, efficient, and atom economic methodology for the preparation of steroid dimers. A set of dimeric androst-16-en es with structurally different dicarboxamide spacers at C-17 was synthesized via one-pot, one-step palladium-cata lyzed aminocar bonylation of 17-iodo-5 a-androst-16-ene (1), which was obtained by the modified Barton's procedure from the correspond ing 17-ketone. The carbonylativ e dimeriza tion reaction leading to steroidal dicarboxami des (2a-2d) took place under relatively mild conditions (30 bar CO, 100 °C), with nearly full conversion of the initial iodo alkenyl steroid in 5 h. The symmetric androst-16-en e ...

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Synthesis of Acyclic Steroid Dimers

Nahar

Sarker

2012

Steroid Dimers

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New steroid dimer derived from cholic acid as receptor for lanthanum(III) and calcium(II) nitrates

Cited by 4 publications

References 32 publications

Glycerol Carbonate Synthesis by Hierarchically Structured Catalysts: Catalytic Activity and Characterization

Glycerol Carbonate Synthesis by Hierarchically Structured Catalysts: Catalytic Activity and Characterization

A new facile synthesis of steroid dimers containing 17,17′-dicarboxamide spacers

Synthesis of Acyclic Steroid Dimers

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