Sharif Digital Repository

An efficient and highly chemoselective synthesis of symmetrical secondary amines via reductive amination of aldehydes with inexpensive and commercially available HMDS and sodium borohydride in high to quantitative yields is reported. © 2008 Elsevier Ltd. All rights reserved  

The synthesis of a series of benzoxazocines has been achieved in good yields by tandem C-alkylation and intramolecular O-alkylation of 1,3-dicarbonyl compounds with quinolinium salts. This is a novel example of the synthesis of eight-membered rings via a tandem process, which provides a method for the synthesis of medium-ring heterocycles  

Silica-supported boron trifluoride (BF3·SiO2) is an efficient, readily available and reusable catalyst for the synthesis of 1,2,4,5-tetrasubstituted imidazoles using benzil, an aromatic aldehyde and an amine in the presence of ammonium acetate. This one-pot procedure is very simple, affording good to excellent yields. © 2008 Elsevier Ltd. All rights reserved  

An efficient and simple method for the reduction of aldehydes, ketones and acid chlorides has been accomplished by using NaBH4-solid LiClO 4 in mild conditions at ambient temperature with complete chemoselectivity in reduction of α,β-unsaturated aldehydes and ketones. The reaction is fast with high yield and simple workup. Copyright © Taylor & Francis, Inc  

The reaction of thiooxindoles with various 2- and 3-substituted pyridinium salts afforded a variety of functionalized thiazocinoindoles. The products have been prepared in good to excellent yields by regioselective dinucleophilic C/S-cyclocondensation of thiooxindoles with pyridinium salts  

The bacterial mechanosensitive channel MscL gates in response to membrane tension as a result of mechanical force transmitted directly to the channel from the lipid bilayer. MscL represents an excellent model system to study the basic biophysical principles of mechanosensory transduction. However, understanding of the essential structural components that transduce bilayer tension into channel gating remains incomplete. Here using multiple experimental and computational approaches, we demonstrate that the amphipathic N-terminal helix of MscL acts as a crucial structural element during tension-induced gating, both stabilizing the closed state and coupling the channel to the membrane. We... 

In this work, graphene oxide (GO) aqueous suspensions prepared by a chemical exfoliation method showed a fluorescence peak at ∼615 nm. Photoluminescence spectroscopy determined that functionalization of the GO sheets by 3-(2-Aminoethylamino) propyltrimethoxysilane molecules significantly quench the fluorescence property of the GO sheets. Fourier transform infrared spectroscopy confirmed proper functionalization of the GO sheets. Curcumin was applied as a fluorescent natural material with an emission peak at ∼550 nm wavelength for green fluorescent labeling of the functionalized-GO sheets. The curcumin-labeled functionalized-GO sheets showed an intense emission band fluorescent property with... 

The reaction of oxiranes with carbon disulfide for preparation of cyclic dithiocarbonates was carried out in water under catalytic amount of an organic base such as dimethylaminopyridine or triethylamine. The reaction conditions are simple and give high yields of desired products.© 2009 HeteroCorporation  

4-Alkyl-2-imino-1,3-dithiolanes and 4-alkyl-2-iminium-1,3-dithiolanes were prepared in excellent yields with complete regiospecificity under mild conditions by the iodocyclization of S-allyl dithiocarbamates. Dehydrohalogenation of the 4-alkyl-2-imino-1,3-dithiolanes gave 4-alkylidene-2-imino-1,3-dithiolanes in excellent yields. © 2009 Elsevier Ltd. All rights reserved  

Nitroamines and nitrothiols were synthesized in high yields by the Michael addition of amines and thiols to nitroolefins without using any catalyst. Also, the reaction of amines with dimethylacetylene dicarboxylate (DMAD) in water afforded the corresponding enamines. © 2007 Elsevier Ltd. All rights reserved  

LiClO4 is used as catalyst for direct Mannich-type reaction of aryl aldehydes, aryl amines, and diethyl malonic ester under solvent-free conditions. This three-component reaction afforded the corresponding β-amino esters in good yields with simple and environmentally benign procedure. Copyright © Taylor & Francis Group, LLC  

At room temperature, ZrOCl2·8H2O on montmorillonite K10 efficiently catalyzes conjugate addition of amines to a variety of conjugated alkenes such as α,β-unsaturated carbonyl compounds, carboxylic esters, nitriles and amides under solvent-free conditions. The catalyst can be recycled for subsequent reactions without any appreciable loss of efficiency. © 2005 Elsevier Ltd. All rights reserved  

A new and efficient synthesis of pyrimido[4,5-d]pyrimidine-2,4-dione derivatives through the reaction of 6-aminouracils and N,N′-bis(arylmethylidene) arylmethane in the presence of molecular iodine as a readily available and feasible catalyst  

The synthesis of new dispiropyrrolidines containing a thiophenone ring has been achieved by a one-pot, three-component 1,3-dipolar cycloaddition reaction. Unsaturated thiophenone dipolarophiles were reacted with azomethine ylides, generated in situ from sarcosine and cycloketone derivatives (isatin, ninhydrin, acenaphthoquinone), to produce the corresponding cycloadducts in good yields (70-90%). The cycloaddition reaction was found to be highly regio- and diastereoselective  

(A) Chakraborty and co-workers have developed a green method for the bulk ring-opening polymerization of lactides in the presence of Cu(OAc)2 as a good catalyst to synthesize polymers with different end-terminal groups.3 These polymerizations are highly controlled leading to the formation of polymers with the expected number of average molecular weights and narrow molecular weight distribution. (B) Garden and co-workers have found that the oxidative addition of anilines with 1,4-naphthoquinone to give N-aryl-2-amino-1,4-naphthoquinones can be performed in the presence of catalytic amounts of copper(II) acetate.4 All the reactions are generally more efficient in that they are cleaner, higher... 

Background: Titanium (Ti) implants are commonly coated with hydroxyapatite (HA). However, HA has some disadvantages such as brittleness, low tensile strength and fracture toughness. It is desirable to combine the excellent mechanical properties of ZrO 2 and the chemical inertness of Al 2O 3 with respect to the purpose of this project which was coating Ti implants with HA-ZrO 2-Al 2O 3 to modify the surface of these implants by adding ZrO 2 and Al 2O 3 to HA. The purpose of this study was to evaluate the efficacy of hydroxyapatite coating nonocomposite. Methods: From September 2009 to January2011, functionally graded HA-Al 2O 3-ZrO 2 and HA coatings were applied on Ti samples. HA-Al 2O 3-ZrO... 

The efficient synthesis of bridged polycyclic naphthooxazocines 3 via addition of naphthalenols 1 as a bis-nucleophile to N-alkylquinolinium salts 2 is described (Scheme 1 and Table 2). This new approach provides a powerful entry into polycyclic structures containing bicyclic N,O-acetals related to bioactive compounds  

A simple, efficient, and practical procedure for the synthesis of imidazo[1,2-a]quinoline and quinolino[1,2-a]quinazoline derivatives using CuO nanoparticles as a novel catalyst in excellent yields is described. The catalyst can be recovered conveniently and reused at least four times without any loss of activity  

An efficient 12-step route for the synthesis of the diterpenoid quinone (±)-danshexinkun A in 23% overall yield from the corresponding highly substituted stilbene using a photocyclization strategy is described