3418-05-1Relevant articles and documents
AMINE-BORANES AS BIFUNCTIONAL REAGENTS FOR DIRECT AMIDATION OF CARBOXYLIC ACIDS
-
Paragraph 0008-0009; 0063-0064, (2022/03/04)
The present invention generally relates to a process for selective and direct activation and subsequent amidation of aliphatic and aromatic carboxylic acids to afford an amide R3CONR1R2. That the process is capable of delivering gaseous or low-boiling point amines provides a major advantage over existing methodologies, which involves an intermediate of triacyloxyborane-amine complex [(R3CO2)3—B—NHR1R2]. This procedure readily produces primary, secondary, and tertiary amides, and is compatible with the chirality of the acid and amine involved. The preparation of known pharmaceutical molecules and intermediates has also been demonstrated.
Amine-boranes as Dual-Purpose Reagents for Direct Amidation of Carboxylic Acids
Choudhary, Shivani,Hamann, Henry J.,Ramachandran, P. Veeraraghavan
supporting information, (2020/11/13)
Amine-boranes serve as dual-purpose reagents for direct amidation, activating aliphatic and aromatic carboxylic acids and, subsequently, delivering amines to provide the corresponding amides in up to 99% yields. Delivery of gaseous or low-boiling amines as their borane complexes provides a major advantage over existing methodologies. Utilizing amine-boranes containing borane incompatible functionalities allows for the preparation of functionalized amides. An intermolecular mechanism proceeding through a triacyloxyborane-amine complex is proposed.
Direct synthesis of amides from nonactivated carboxylic acids using urea as nitrogen source and Mg(NO3)2or imidazole as catalysts
Blacker, A. John,Chhatwal, A. Rosie,Lomax, Helen V.,Marcé, Patricia,Williams, Jonathan M. J.
, p. 5808 - 5818 (2020/06/21)
A new method for the direct synthesis of primary and secondary amides from carboxylic acids is described using Mg(NO3)2·6H2O or imidazole as a low-cost and readily available catalyst, and urea as a stable, and easy to manipulate nitrogen source. This methodology is particularly useful for the direct synthesis of primary and methyl amides avoiding the use of ammonia and methylamine gas which can be tedious to manipulate. Furthermore, the transformation does not require the employment of coupling or activating agents which are commonly required.
Tuning the solid-state emission of the analogous GFP chromophore by varying alkyl chains in the imidazolinone ring
Shen, Xiang,Huang, Guangxi,Li, Kan,Zhang, Guanxin,Zhang, Deqing
, p. 1197 - 1203 (2013/09/23)
New analogues of green fluorescent protein (GFP) chromophore m GFP-C n (n = 1, 3, 5, 11) with alkyl chains of different lengths in the imidazolinone rings were synthesized and their crystal structures were determined. These GFP-like chromophores are all emissive in the solid state. And the solid-state emission quantum yields of increase by extending the lengths of alkyl chains, owing to the fact that the intermolecular pi-pi interactions are significantly weakened based on their crystal structures.
Efficient tandem process for the catalytic deprotection of N-allyl amides and lactams in aqueous media: A novel application of the bis(allyl)- ruthenium(IV) catalysts [Ru(η3:η2: η3-C12H18)Cl2] and [Ru(η3:η3-C10H16)-(μ-Cl) Cl}2]
Cadierno, Victorio,Gimeno, Jose,Nebra, Noel
, p. 6590 - 6594 (2008/03/13)
An operationally simple and highly efficient methodology for the removal of the allyl protecting group in amides and lactams has been developed by using the commercially available bis(allyl)-ruthenium(IV) catalysts [Ru(η3:η2:η3-C12H 18)Cl2] (C12H18 = dodeca-2,6,10-triene-1,12-diyl) and [(Ru(η3:η3- C10H16)(μ-Cl)Cl}2] (C10H 16 = 2,7-dimethylocta-2,6-diene-1,8-diyl). The tandem process, which takes place in aqueous media and proceeds in a one-pot manner, involves the initial isomerization of the C=C bond of the allyl unit and subsequent oxidative cleavage of the resulting enamide.
Towards supramolecular fixation of NOx gases: Encapsulated reagents for nitrosation
Kang, Yanlong,Zyryanov, Grigory V.,Rudkevich, Dmitry M.
, p. 1924 - 1932 (2007/10/03)
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 5a-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 NO 2/ 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 6d,e were obtained with ～30% yields, while bulkier amides were nitrosated with much lower yields (+ 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.
Encapsulated reagents for nitrosation
Zyryanov, Grigory V.,Rudkevich, Dmitry M.
, p. 1253 - 1256 (2007/10/03)
(Matrix presented) A novel class of stable, mild, and size-shape-selective nitrosating agents for secondary amides is introduced. These are based on reversible entrapment and release of reactive nitrosonium species by calix[4]arenes. The NO+ encapsulation controls the reaction selectivity.
Long-range anisotropic effects of long chain amides
Budzikiewicz, Herbert,Vieth, Peter-Eric,Krueger, Uwe
, p. 825 - 840 (2007/10/02)
In 1H-NMR spectra of amids with long-chain aliphatic N-substituents one observes - despite of the free mobility of the aliphatic chain - splitting of the signals of the terminal methyl groups which is caused by the hindered rotation of the amide bond. - Keywords: Amides; Hindered rotation; 1H-NMR
