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Facile Cleavage (facile + cleavage)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Facile Cleavage of Si,C Bonds during the Sol-Gel Hydrolysis of Aminomethyltrialkoxysilanes , A New Method for the Methylation of Primary Amines

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 12 2004
Augustin Adima
Abstract The reaction of chloromethyltriethoxysilane with (1R,2R)-bis(methylamino)cyclohexane (1) afforded the corresponding bis-silylated compound 2. The sol-gel hydrolysis of 2 did not give the expected bridged silsesquioxane owing to quantitative Si,C-bond cleavage. Instead, silica and (1R,2R)-bis(dimethylamino)cyclohexane (3) were obtained. This reaction was exploited to propose a new route for the methylation of amines. Such methylation reaction of amines could be extended to other amines and provides a new method for the selective monomethylation of primary amines. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Facile Cleavage of Si,C Bonds During the Sol,Gel Hydrolysis of Aminomethyltrialkoxysilanes , A New Method for the Methylation of Primary Amines.

CHEMINFORM, Issue 40 2004
Augustin Adima
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

A Facile Cleavage of the Carbon-Nitrogen Bond of Aromatic Imines Using Acylation Reagents in the Presence of Catalytic Amounts of Ytterbium Triflate.

CHEMINFORM, Issue 39 2004
Weike Su
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

A novel thermostable hemoglobin from the actinobacterium Thermobifida fusca

FEBS JOURNAL, Issue 16 2005
Alessandra Bonamore
The gene coding for a hemoglobin-like protein (Tf-trHb) has been identified in the thermophilic actinobacterium Thermobifida fusca and cloned in Escherichia coli for overexpression. The crystal structure of the ferric, acetate-bound derivative, was obtained at 2.48 Å resolution. The three-dimensional structure of Tf-trHb is similar to structures reported for the truncated hemoglobins from Mycobacterium tuberculosis and Bacillus subtilis in its central domain. The complete lack of diffraction patterns relative to the N- and C-terminal segments indicates that these are unstructured polypeptides chains, consistent with their facile cleavage in solution. The absence of internal cavities and the presence of two water molecules between the bound acetate ion and the protein surface suggest that the mode of ligand entry is similar to that of typical hemoglobins. The protein is characterized by higher thermostability than the similar mesophilic truncated hemoglobin from B. subtilis, as demonstrated by far-UV CD melting experiments on the cyano-met derivatives. The ligand-binding properties of Tf-trHb, analyzed in stopped flow experiments, demonstrate that Tf-trHb is capable of efficient O2 binding and release between 55 and 60 °C, the optimal growth temperature for Thermobifida fusca. [source]

Synthesis, characterization and hydroformylation activity of 7-azaindolate-bridged dinuclear rhodium(I)phosphines with pendant polar-groups

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 11 2009
Chandra Sekhar Vasam
Abstract New dinuclear Rh(I),Phosphines of the types [Rh(µ-azi)(CO)(L)]2 (1,3,7) and [Rh(µ-azi)(L)]2 (8) with pendant polar groups, and a chealated mononuclear compound [Rh(azi-H)(CO)(L)] (2) (where azi = 7-azaindolate, L = polar phosphine) were isolated from the reaction of [Rh(µ-Cl)(CO)2]2 with 7-azaindolate followed by some polar mono - and bis -phosphines (L1,L8). A relationship between ,,31P-NMR and ,(CO) values was considered to define the impact of polar-groups on ,-donor properties of the phosphines. These compounds were evaluated as catalyst precursors in the hydroformylation of 1-hexene and 1-dodecene both in mono- and biphasic aqueous organic systems. While the biphasic hydroformylations (water + toluene) gave exclusively the aldehydes, the monophasic one (aqueous ethanol) showed propensity to form both aldehydes and alcohols. The influence of bimetallic cooperative effects, and ,-donor and hydrophilic properties of the phosphines with pendant polar-groups in enhancing the yields and selectivity of hydroformylation products was emphasized. In addition, when strong ,-donor phosphine was used, the ,-acceptor nature of pyridine ring of 7-azaindolate spacer was found to be a considerable factor in facilitating the facile cleavage of CO group during hydroformylation and in supplementing the cooperative effects. Copyright © 2009 John Wiley & Sons, Ltd. [source]