نتایج جستجو برای: amides
تعداد نتایج: 3739 فیلتر نتایج به سال:
A novel amidase involved in bacterial cyclic imide metabolism was purified from Blastobacter sp. strain A17p-4. The enzyme physiologically functions in the second step of cyclic imide degradation, i.e., the hydrolysis of monoamidated dicarboxylates (half-amides) to dicarboxylates and ammonia. Enzyme production was enhanced by cyclic imides such as succinimide and glutarimide but not by amide co...
Serine carboxypeptidases have the ability to hydrolyze peptides as well as peptide amides. Previously, it has been demonstrated that Asn51 and Glu145 (in the protonated form) each donate a hydrogen bond to the alpha-carboxylate of peptide substrate. It is here demonstrated by characterization of carboxypeptidase Y derivatives, mutationally altered at positions 51 and 145, that the same groups a...
Simple borates serve as effective promoters for amide bond formation with a variety of carboxylic acids and amines. With trimethyl or tris(2,2,2-trifluoroethyl) borate, amides are obtained in good to excellent yield and high purity after a simple work-up procedure. Tris(2,2,2-trifluoroethyl) borate can also be used for the straightforward conversion of primary amides to secondary amides via tra...
A flexible, modular ynamide synthesis is reported that uses trichloroethene as an inexpensive two carbon synthon. A wide range of amides and electrophiles can be converted to the corresponding ynamides, importantly including acyclic carbamates, hindered amides, and aryl amides. This method thus overcomes many of the limitations of other approaches to this useful functionality.
The internal strain in cyclic amides are explained as a factor of resonance that are effected on the bond length C-N and are a major factor of rates of hydrolysis. The cyclic amides in this study are optimized by Gaussian program and the bond length of C-N in the rings are studied by HF/6-31G*.
The internal strain in cyclic amides are explained as a factor of resonance that are effected on the bond length C-N and are a major factor of rates of hydrolysis. The cyclic amides in this study are optimized by Gaussian program and the bond length of C-N in the rings are studied by HF/6-31G*.
A novel synthesis of anhydrides from twisted amides is reported. Sc(OTf)3 catalysis in the presence of water is used to synthesize anhydrides in one step from amides without external nucleophiles. Mechanistic studies indicate that the coordination of the catalyst is critical to induce the challenging N-C activation step. This process further highlights the utility of twisted amides in organic s...
Mesoporous MCM-41 silicas anchored with sulfonic acid (–SO3H) groups (denoted MSN-SA) via postsynthesis modification are very effective for the Beckman rearrangement. A simple and convenient procedure for conversion of a variety oximes to their corresponding amides and lactams has been developed. The reaction was carried out in the presence of MSN-SA as the catalyst. The best results for conver...
Seventy-three N,N-disubstituted amides of long-chain, principally C(18), fatty acids were screened for antimicrobial activity against bacteria, yeasts, and molds. Amides containing an epoxy group exhibit a broad spectrum of antimicrobial activity which is further enhanced by unsaturation. Mono-unsaturation alone does not contribute a broad level of activity to the N,N-disubstituted amides of th...
The Action of Liquid-Ammonia Solutions of Ammono Acids on Metallic Amides, Imides, and Nitrides. The acid amides and imides, and the metallic derivatives of the acid amides and imides are the acds, bases, and salts respectively of an ammonia system of acids, bases, and salts.1 Guided by the relationships implied in the above statement Franklin and Stafford were able to prepare potassium derivat...
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