نتایج جستجو برای: regio and chemoselective

تعداد نتایج: 16827812  

1,1’-(Ethane-1,2-diyl)dipyridinium bistribromide (EDPBT) was used as a chemoselective and effective organocatalyst for the silylation of hydroxyl groups as well as desilylation of trimethylsilyl ethers under mild conditions at room temperature with good to excellent yields.

Journal: :Chemical communications 2008
Xiaobing Yang Liangbing Gan Zheming Wang

Addition of the ambident SCN group to a fullerendione derivative follows two different pathways in the presence and absence of Lewis acid.

2004
Robert E. Grimm Roger J. Phillips

Introduction. Eistla Regio is a broad, low, discontinuous topographic rise striking roughly EW at low northern latitudes of Venus. Some 2000x7000 km in dimension, it is the third largest rise in planform on Venus after Aphrodite Terra and Beta-Phoebe Regiones. These rises are the key physiographic elements in a hot-spot model of global tectonics [1] including transient plume behavior [2]. Since...

Journal: Nanochemistry Research 2016

A mild, green and highly efficient route for regio-selective amination of oxiranes was developed via incorporation of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) cations onto the surface of hydroxyapatite-encapsulated γ-Fe2O3 nanoparticles (γ-Fe2O3@HAp). Among six magnetically recoverable catalytic systems denoted as [γ-Fe2O3@HAp-MII], the catalyst in which M designated as Fe(II) showed t...

2007
SCOTT L. MURCHIE JAMES W. HEAD

A system of arcuate furrows in Galileo Regio and Marius Regio, two large blocks of ancient dark terrain, has previously been proposed to be the remnant of an originally more concentric furrow set that was disrupted by shear. Estimates of the two regions' poles of furrow concentricity indicate a considerable westward offset of the Galileo Regio pole. These measurements uggest he possibility of a...

Journal: :Chemical communications 2005
Sengodagounder Muthusamy Janagiraman Krishnamurthi Munirathnam Nethaji

The reverse regio- and diastereoselectivities are observed between the reactions involving 5- and 6-membered-ring cyclic carbonyl ylide dipoles with alpha-methylene ketones. A mild catalytic route to synthesize spirocyclic systems with high regio-, chemo- and diastereoselectivities is described.

Journal: :Chemical communications 2010
Fumihiro Amemiya Keishi Fuse Toshio Fuchigami Mahito Atobe

A new strategy for chemoselective reaction using a two inlet micro-flow reactor is described. In this system, the combined use of suitable flow mode and corresponding cathode material enables chemoselective cathodic reduction to control the product regioselectivity in carbonyl allylation.

Journal: :iranian journal of science and technology (sciences) 2013
a. z. sardarian

4-dodecylbenzenesulfonic acid (dbsa) has been shown to be an efficient, mild, green, stable and chemoselective brønsted acid catalyst for the synthesis of 1, 1-diacetates (acylals) of aldehydes under solvent-free conditions. the mild condition, eco-friendly, excellent yields, short reaction times and using an easily available, inexpensive and reusable catalyst are important features of this met...

-A simple, efficient, and general method has been developed for the chemoselective acetalization of aldehydes with 1,3-propanediol, 1,2-ethanediol and trimethyl orthoformate in the presence of solid lithium perchlorate under solvent-free conditions. Both cyclic and acyclic acetals of aldehydes were obtained under environmentally benign conditions in good to excellent yields.

Journal: :iranian journal of science and technology (sciences) 2015
s. rezayati

an efficient and chemoselective procedure for the preparation of 1, 1-diacatates (acylals) from various aldehydes with acetic anhydride in the presence of brønsted acidic ionic liquid [msei]cl as a reusable catalytic system under solvent-free condition at room temperature and short periods of times with excellent yields will be described. the catalyst was easily separated in simple work-up and ...

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