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Secondary Amides (secondary + amide)
Selected AbstractsGeneral and Chemoselective N-Transacylation of Secondary Amides by Means of Perfluorinated Anhydrides,ANGEWANDTE CHEMIE, Issue 10 2010Paola Rota Dr. Zahlreiche funktionelle Gruppen, die unter den Bedingungen der klassischen N-Transacylierung hydrolysiert werden, werden toleriert, wenn die N-Transacylierung über perfluorierte Analoga verläuft, die anschließend zu einem normalen Amid umgesetzt werden können (siehe Schema). [source] ChemInform Abstract: General and Chemoselective N-Transacylation of Secondary Amides by Means of Perfluorinated Anhydrides.CHEMINFORM, Issue 27 2010Paola Rota Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A Practical and Effective Ruthenium Trichloride-Based Protocol for the Regio- and Stereoselective Catalytic Hydroamidation of Terminal AlkynesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2008Lukas Abstract A rational catalyst development based on mechanistic and spectroscopic investigations led to the discovery of a new protocol for catalytic hydroamidation reactions that draws on easily available ruthenium trichloride trihydrate (RuCl3,3,H2O) as the catalyst precursor instead of the previously employed, expensive bis(2-methylallyl)(1,5-cyclooctadiene)ruthenium(II). This practical and easy-to-use protocol dramatically improves the synthetic applicability of Ru-catalyzed hydroamidations. The catalyst, generated in situ from ruthenium(III) chloride hydrate, tri- n -butylphosphine, 4-(dimethylamino)pyridine and potassium carbonate, effectively promotes the addition of secondary amides, lactams and carbamates to terminal alkynes under formation of (E)- anti -Markovnikov enamides. The scope of the new protocol is demonstrated by the synthesis of 24 functionalized enamide derivatives, among them valuable intermediates for organic synthesis. [source] (,)-Sparteine-Mediated Directed ortho- Metalation of N -Cumyl- N -ethylferrocenecarboxamide.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 3 2003Amines, Esters, Phosphines, Versatile Routes to Functionalized Planar Chiral Ferrocenecarboxamides Abstract N -Cumyl- N -ethylferrocenecarboxamide 5 provides planar chiral carboxamides 6 in high yield and % ee via (,)-sparteine-mediated directed ortho -metalation. Mild decumylation affords secondary amides 7, which serve as intermediates for a convenient and general route to the venerable Ugi planar chiral ferrocenylamines 13 and as versatile precursors for the preparation of novel chiral ferrocenes 15 and 20. The chiral TMS-ferrocenyl derivative 7c is used to prepare the enantiomeric (S)- 7f, circumventing the lack of availability of (+)-sparteine. [source] The mechanism of alkaline hydrolysis of amides: a comparative computational and experimental study of the hydrolysis of N -methylacetamide, N -methylbenzamide, and acetanilideJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 6 2009Diana Cheshmedzhieva Abstract Theoretical computations and experimental kinetic measurements were applied in studying the mechanistic pathways for the alkaline hydrolysis of three secondary amides: N -methylbenzamide, N -methylacetamide, and acetanilide. Electronic structure methods at the HF/6-31+G(d,p) and B3LYP/6-31+G(d,p) levels of theory are employed. The energies of the stationary points along the reaction coordinate were further refined via single point computations at the MP2/6-31+G(d,p) and MP2/6-311++G(2d,2p) levels of theory. The role of water in the reaction mechanisms is examined. The theoretical results show that in the cases of N -methylbenzamide and N -methylacetamide the process is catalyzed by an ancillary water molecule. The influence of water is further assessed by predicting its role as bulk solvent. The alkaline hydrolysis process in aqueous solution is characterized by two distinct free energy barriers: the formation of a tetrahedral adduct and its breaking to products. The results show that the rate-determining stage of the process is associated with the second transition state. The entropy terms evaluated from theoretical computations referring to gas-phase processes are significantly overestimated. The activation barriers for the alkaline hydrolysis of N -methylbenzamide and acetanilide were experimentally determined. Quite satisfactory agreement between experimental values and computed activation enthalpies was obtained. Copyright © 2008 John Wiley & Sons, Ltd. [source] Interplay between dipolar, stacking and hydrogen-bond interactions in the crystal structures of unsymmetrically substituted esters, amides and nitriles of (R,R)- O,O,-dibenzoyltartaric acidACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2001Urszula Rychlewska The compounds analysed are the O,O,-dibenzoyl derivatives of (R,R)-tartaric acid, asymmetrically substituted by ester, amide and nitrile groups. Benzoylation does not introduce drastic changes to the molecular conformation. All investigated molecules adopt the planar T conformation of the four-carbon chain with noticeably smaller departures from the ideal conformation than observed in the nonbenzoylated analogs. Primary and secondary amides always orient the C=O bond antiperiplanar (a) with respect to the nearest C*,O bond, while methylester groups adjust their conformation to that adopted by the amide substituent situated at the other end of the molecule. Tertiary amides and carboxyl groups place their carbonyls at the same side as the nearest C*,O bond (the s form), but often deviations from coplanarity of the two bonds are significant and higher than those observed in the nonbenzoylated series. The results presented demonstrate the importance of dipole/dipole interactions between CO and ,C*H groups in stabilizing the molecular conformation, and between carbonyl groups in stabilizing crystal packing of the molecules that lack classical hydrogen-bond donor groups. An illustration is provided as to how a small change in mutual orientation of molecules arranged in a close-packed fashion causes a change in the character of intermolecular interactions from van der Waals to sandwich stacking between the benzoyloxy phenyls, and to dipolar between the benzoyloxy carbonyls. Hydrogen-bonded molecules tend to orient in a head-to-tail mode; the head-to-head arrangement being limited to cases in which terminal carbonyl groups are situated at one side of the molecule. The orientation of the benzoyloxy substituents with respect to the carbon main chain is such that the (O=)C,O,C,H bond system often deviates significantly from planarity. [source] Towards Supramolecular Fixation of NOX Gases: Encapsulated Reagents for NitrosationCHEMISTRY - A EUROPEAN JOURNAL, Issue 6 2005Yanlong Kang Abstract The use of simple calix[4]arenes for chemical conversion of NO2/N2O4 gases is demonstrated in solution and in the solid state. Upon reacting with these gases, calixarenes 1 encapsulate nitrosonium (NO+) cations within their cavities with the formation of stable calixarene,NO+ complexes 2. These complexes act as encapsulated nitrosating reagents; cavity effects control their reactivity and selectivity. Complexes 2 were effectively used for nitrosation of secondary amides 5, including chiral derivatives. Unique size,shape selectivity was observed, allowing for exclusive nitrosation of less crowded N -Me amides 5,a,e (up to 95,% yields). Bulkier N -Alk (Alk>Me) substrates 5 did not react due to the hindered approach to the encapsulated NO+ reagents. Robust, silica gel based calixarene material 3 was prepared, which reversibly traps NO2/N2O4 with the formation of NO+ -storing silica gel 4. With material 4, similar size,shape selectivity was observed for nitrosation. The N -Me,N -nitroso derivatives 6,d,e were obtained with ,30,% yields, while bulkier amides were nitrosated with much lower yields (<8,%). Enantiomerically pure encapsulating reagent 2,d was tested for nitrosation of racemic amide 5,t, showing modest but reproducible stereoselectivity and ,15,% ee. Given high affinity to NO+ species, which can be generated by a number of NOX gases, these supramolecular reagents and materials may be useful for NOX entrapment and separation in the environment and biomedical areas. [source] | ||||||||||||||||||||||