One-pot hydrosilylation-protodesilylation of functionalized diarylalkynes: a highly selective access to Z-stilbenes. Application to the synthesis of combretastatin A-4

An efficient stereoselective synthesis of Z-stilbenes has been developed from diarylalkynes via a new hydrosilylation-protodesilylation process. The scope and limitation of this method is presented to stereoselectively prepare a wide range of (Z)-stilbenes in a one-pot way is presented. A concise application to the preparation of combretastatin A-4 (CA-4), a vascular targeting agent inhibitor of tubulin polymerisation is described.     

Palladium-catalyzed stereoselective synthesis of E- and Z-1,1-diaryl or triarylolefins

A stereoselective and flexible synthesis of various E- and Z-1,1-diaryl and triarylolefins 3 was achieved from readily available vinylstannanes 1 via stereospecific iodo-destannylation and subsequent palladium-catalyzed Negishi-type cross-coupling reaction with arylzinc reagents under mild conditions.     

Regiocontrol of the palladium-catalyzed tin hydride addition to Z-enynols: remarkable Z-directing effects

Palladium-catalyzed hydrostannation of substituted Z- and E-enynols is discussed and compared. The regioselectivity of the H-Sn bond addition was found to be controlled by the geometry of the double bond (Z- or syn-directing effect) rather than the nature of its substituents. Exclusively alpha-vinyl stannanes were obtained from Z-enynols having various substituents on the double bond regardless of their electronic, steric, or chelating natures.     

Synthesis of new racemic α-heterocyclic α,α-diaminoesters and α-aminoester carboxylic

New racemic α-aminoester and α,α-diaminoesters derivatives were synthesized by nucleophilic substitution of methyl α-azido glycinate N-benzoylated with 3-amino-1,2,4-triazole, 2-tetrahydrofuran-2-ylmethan-amine and 2-methyl quinolin-4-amine.     

Synthesis and Biological Activity of 3-(Heteroaryl)quinolin-2(1H)-ones Bis-Heterocycles as Potential Inhibitors of the Protein Folding Machinery Hsp90

In the context of our SAR study concerning 6BrCaQ analogues as C-terminal Hsp90 inhibitors, we designed and synthesized a novel series of 3-(heteroaryl)quinolin-2(1H), of types 3, 4, and 5, as a novel class of analogues. A Pd-catalyzed Liebeskind–Srogl cross-coupling was developed as a convenient approach for easy access to complex purine architectures. This series of analogues showed a promising biological effect against MDA-MB231 and PC-3 cancer cell lines. This study led to the identification of the best compounds, 3b (IC₅₀ = 28 µM) and 4e, which induce a significant decrease of CDK-1 client protein and stabilize the levels of Hsp90 and Hsp70 without triggering the HSR response.     

Experimental investigation of the effect of variously-shaped ribs on local heat transfer on the outer wall of the turning portion of a U-channel inside solar air heater

In the present work, an experimental investigation of convective heat transfer and pressure drop was carried out for the turning portion of a U-channel where the outer wall was equipped with ribs. The shape of the ribs was varied. The investigation aims to give guidelines for improving the thermo-hydraulic performance of a solar air heater at the turning portion of a U-channel. Both the U-channel and the ribs were made in acrylic material to allow optical access for measuring the surface temperature by using a high-resolution technique based on narrow band thermochromic liquid crystals (TLC R35C5 W) and a CCD camera placed to face the turning portion of the U-channel. The uncertainties were estimated to 5 and 7 % for the Nusselt number and friction factor, respectively. The pressure drop was approximately the same for all the considered shapes of the ribs while the dimpled rib case gave the highest heat transfer coefficient while the grooved rib presented the highest performance index.     

Platinum oxide catalyzed silylation of aryl halides with triethylsilane: an efficient synthetic route to functionalized aryltriethylsilanes

[STRUCTURE: SEE TEXT] The first platinum-catalyzed selective silylation of aryl halides including aryl iodides and bromides having an electron-withdrawing group is described. The reaction takes place rapidly in NMP with triethylsilane as a silicon source and sodium acetate to provide functionalized aryltriethylsilanes in moderate to good yields. Heteroaromatic halides also were found to be readily silylated with triethylsilane. The procedure is chemoselective and tolerates a wide variety of functional groups.     

Intercalation of xylenol orange, morin and calmagite into NaY zeolite and their application in dye/zeolite modified electrode

The intercalation of xylenol orange, morin and Calmaigite into NiaY zeolite were studied by XRD, TGA, and BET and diffuse reflectance. These dye incorporated into NaY zeolite by ion exchange in aqueous phase. Results show that xylenol orange can be intercalating better into zeolite. The dye molecules are strongly retained in the channels of zeolites. The prepared intercalated dye/zeolite, for the first time, was used as the modifier for carbon past electrode. The dye/zeolite modified carbon paste electrode was developed for the voltammetric determination of Cu(II). Copper(II) was selectively preconcentrated. Results shows the peak current intensity increased in order of calmagite > xylenol orange > morin dyes intercalated in zeolite. The results agree with complex formation of those dyes as chelating agents with Copper(II).