Mono- and double carbonylation of aryl iodides with amine nucleophiles in the presence of recyclable palladium catalysts immobilised on a supported dicationic ionic liquid phase

Silica modified with organic dicationic moieties proved to be an excellent support for palladium catalysts used in the aminocarbonylation of aryl iodides. By an appropriate choice of the reaction conditions, the same catalyst could be used for selective mono- or double carbonylations leading to amide and [small alpha]-ketoamide products, respectively. The best catalyst could be recycled for at least 10 consecutive runs with a loss of palladium below the detection limit. By the application of the new support, efficient catalyst recycling could be achieved under mild reaction conditions (under low pressure and in a short reaction time). Palladium-leaching data support a mechanism with dissolution-re-precipitation of the active palladium species

Synthesis of Novel Ferrocene-Benzofuran Hybrids via Palladium- and Copper-Catalyzed Reactions

The combination of the ferrocene skeleton with pharmacophores often leads to molecules with interesting biological properties. Five ferrocene-benzofuran hybrids of different structures were synthesized by transition metal catalyzed reactions. The efficiency of both homogeneous and heterogeneous catalytic methods was tested. The products were characterized using 1H, 13C NMR and FTIR spectroscopy, HRMS and cyclic voltammetry. The structure of one of the new compounds was also proved with X-ray crystallography. The new hybrids showed moderate cytotoxicity on MCF-7 and MDA-MB-231 cell lines. It is remarkable that the less curable MDA-MB-231 cell line was more sensitive to treatment with three ferrocene derivatives

Steroidal Ferrocenes as Potential Enzyme Inhibitors of the Estrogen Biosynthesis

The potential inhibitory efect of diverse triazolyl-ferrocene steroids on key enzymes of the estrogen biosynthesis was investigated. Test compounds were synthesized via copper-catalyzed cycloaddition of steroidal azides and ferrocenylalkynes using our efcient methodology published previously. Inhibition of human aromatase, steroid sulfatase (STS) and 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1) activities was investigated with in vitro radiosubstrate incubations. Some of the test compounds were found to be potent inhibitors of the STS. A compound bearing ferrocenyl side chain on the C-2 displayed a reversible inhibition, whereas C-16 and C-17 derivatives displayed competitive irreversible binding mechanism toward the enzyme. 17α-Triazolyl-ferrocene derivatives of 17β-estradiol exerted outstanding inhibitory efect and experiments demonstrated a key role of the ferrocenyl moiety in the enhanced binding afnity. Submicromolar IC50 and Ki parameters enroll these compounds to the group of the most efective STS inhibitors published so far. STS inhibitory potential of the steroidal ferrocenes may lead to the development of novel compounds able to suppress in situ biosynthesis of 17β-estradiol in target tissues

N,N-Bis(3β-acetoxypregn-5(6)-en-20-on-16α-yl)hydroxylamine

A steroid with the dimeric structure, N,N-bis(3β-acetoxypregn-5(6)-en-20-on-16α-yl)hydroxylamine was synthesized in the base catalyzed reaction of 3β-acetoxypregn-5,16-dien-20-one with O-(trimethylsilyl)hydroxylamine. The structure of the product was determined by NMR (including 2D techniques), FAB MS, IR spectroscopy and elemental analysis

The Use of Supported Acidic Ionic Liquids in Organic Synthesis

Catalysts obtained by the immobilisation of acidic ionic liquids (ILs) on solid supports offer several advantages compared to the use of catalytically active ILs themselves. Immobilisation may result in an increase in the number of accessible active sites of the catalyst and a reduction of the amount of the IL required. The ionic liquid films on the carrier surfaces provide a homogeneous environment for catalytic reactions but the catalyst appears macroscopically as a dry solid, so it can simply be separated from the reaction mixture. As another advantage, it can easily be applied in a continuous fixed bed reactor. In the present review the main synthetic strategies towards the preparation of supported Lewis acidic and Brønsted acidic ILs are summarised. The most important characterisation methods and structural features of the supported ionic liquids are presented. Their efficiency in catalytic reactions is discussed with special emphasis on their recyclability

Urea-Functionalized Heterocycles: Structure, Hydrogen Bonding and Applications

Ureido-heterocycles exhibiting different triple- and quadruple H-bonding patterns are useful building blocks in the construction of supramolecular polymers, self-healing materials, stimuli-responsive devices, catalysts and sensors. The heterocyclic group may provide hydrogen bond donor/acceptor sites to supplement those in the urea core, and they can also bind metals and can be modified by pH, redox reactions or irradiation. In the present review, the main structural features of these derivatives are discussed, including the effect of tautomerization and conformational isomerism on self-assembly and complex formation. Some examples of their use as building blocks in different molecular architectures and supramolecular polymers, with special emphasis on biomedical applications, are presented. The role of the heterocyclic functionality in catalytic and sensory applications is also outlined

Facile synthesis of 12-carboxamido-11-spirostenes via palladium-catalyzed carbonylation reactions

12-Carboxamido- and 12-carboxyl-11-spirostenes were synthesized from the corresponding 12-iodo-11-ene derivative in palladium-catalyzed carbonylation reactions under mild reaction conditions. The synthesis of the iodo-alkene substrate is based on the transformation of the 12-keto derivative (hecogenin) to hydrazone, which was treated with iodine in the presence of a base (1,1,3,3-tetramethyl guanidine). While various 12-carboxamides were synthesized in moderate to high yields by using simple alkyl/arylamines or amino acid methylesters as N-nucleophiles, low yields can be achieved with alcohols as O-nucleophiles. The homogeneous carbonylation reactions tolerate the 3-hydroxy substituent and the spiroacetal moiety.http://www.sciencedirect.com/science/article/B6TC9-4KBX4P7-1/1/9ccb758281b9b11e5e0e07e137f9015