541-16-2Relevant articles and documents
Methanofullerene Molecular Scaffolding: Towards C60-Substituted Poly(triacetylenes) and Expanded Radialenes, Preparation of a C60-C70 Hybrid Derivative, and a Novel Macrocyclization Reaction
Nierengarten, Jean-Francois,Herrmann, Andreas,Tykwinski, Rik R.,Ruettimann, Markus,Diederich, Francois,Boudon, Corinne,Gisselbrecht, Jean-Paul,Gross, Maurice
, p. 293 - 316 (1997)
The synthesis of (E)-hex-3-ene-1,5-diynes and 3-methylidenepenta-1,4-diynes with pendant methano[60]-fullerene moieties as precursors to C60-substituted poly(triacetylenes) (PTAs, Fig. 1) and expanded radialenes (Fig. 2) is described. The Bingel reaction of diethyl (E)-2,3-dialkynylbut-2-ene-1,4-diyl bis(2-bromopropanedioates) 5 and 6 with two C60 molecules (Scheme 2) afforded the monomeric, silyl-protected PTA precursors 9 and 10 which, however, could not be effectively desilylated (Scheme 4). Also formed during the synthesis of 9 and 10, as well as during the reaction of C60 with the desilylated analogue 16 (Scheme 5), were the macrocyclic products 11, 12, and 17, respectively, resulting from double Bingel addition to one C-sphere. Rigorous analysis revealed that this novel macrocyclization reaction proceeds with complete regio- and diastereoselectivity. The second approach to a suitable PTA monomer attempted N,N′-dicyclohexylcarbodiimide(DCC)-mediated esterification of (E)-2,3-diethynylbut-2-ene-1,4-diol (18, Scheme 6) with mono-esterified methanofullerene-dicarboxylic acid 23; however, this synthesis yielded only the corresponding decarboxylated methanofullerene-carboxylic ester 27 (Scheme 7). To prevent decarboxylation, a spacer was inserted between the reacting carboxylic-acid moiety and the methano C-atom in carboxymethyl ethyl 1,2-methano[60]fullerene-61,61-dicarboxylate (28, Scheme 8), and DCC-mediated esterification with diol 18 afforded PTA monomer 32 in good yield. The formation of a suitable monomeric precursor 38 to C60-substituted expanded radialenes was achieved in 5 steps starting from dihydroxyacetone (Schemes 9 and 10), with the final step consisting of the DCC-mediated esterification of 28 with 2-[1-ethynyl(prop-2-ynylidene)]propane-1,3-diol (33). The first mixed C60-C70 fullerene derivative 49, consisting of two methano[60]fullerenes attached to a methano[70]fullerene, was also prepared and fully characterized (Scheme 13). The Cs-symmetrical hybrid compound was obtained by DCC-mediated esterification of bis[2-(2-hydroxyethoxy)ethyl] 1,2-methano[70]fullerene-71,71-dicarboxylate (46) with an excess of the C60-carboxylic acid 28. The presence of two different fullerenes in the same molecule was reflected by its UV/VIS spectrum, which displayed the characteristic absorption bands of both the C70 and C60 mono-adducts, but at the same time indicated no electronic interaction between the different fullerene moieties. Cyclic voltammetry showed two reversible reduction steps for 49, and comparison with the corresponding C70 and C60 mono-adducts 46 and 30 indicated that the three fullerenes in the composite fullerene compound behave as independent redox centers.
Size-selective mesoporous silica-based Pt(II)complex as efficient and reusable photocatalytic material
González-Mu?oz, Daniel,Casado-Sánchez, Antonio,del Hierro, Isabel,Gómez-Ruiz, Santiago,Cabrera, Silvia,Alemán, José
, p. 374 - 383 (2019/05/01)
The grafting of a Pt(II)photocatalyst into three different mesoporous silica-based materials with different particle sizes and pore sizes was easily achieved through an amide bond formation. The analysis and results of the different characterization techniques showed that the catalyst is immobilized inside the pores of the materials and the photophysical properties of the catalyst are preserved after the covalent anchoring. The photocatalytic material catalyzed efficiently the debromination reaction of different substrates and is reused without detriment in its catalytic activity. In addition, the incorporation of the catalyst into mesoporous silica materials with different pore size allows the selective debromination of substrates by size discrimination.
Process for preparing C5 products and their use for Atorvastatin synthesis
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Page/Page column 17, (2010/11/23)
The present invention relates to a process for preparing C5 intermediates and their use in the preparation of pyrrole derivatives of a class that is effective at inhibiting the biosynthesis of cholesterol in humans, and more particularly to improved synthetic methods for preparing 3,5-dihydroxy-7-pyrrol-1-yl heptanoic acids from 1,4-diketo starting materials. The invention further relates to intermediates in this process
