3392-91-4Relevant academic research and scientific papers
Graphene oxide: A convenient metal-free carbocatalyst for facilitating amidation of esters with amines
Patel, Khushbu P.,Gayakwad, Eknath M.,Shankarling, Ganapati S.
, p. 2661 - 2668 (2020/02/20)
Herein, we report a graphene oxide (GO) catalyzed condensation of non-activated esters and amines, that can enable diverse amides to be synthesized from abundant ethyl esters forming only volatile alcohol as a by-product. GO accelerates ester to amide conversion in the absence of any additives, unlike other catalysts. A wide range of ester and amine substrates are screened to yield the respective amides in good to excellent yields. The improved catalytic activity can be ascribed to the oxygenated functionalities present on the graphene oxide surface which forms H-bonding with the reactants accelerating the reaction. Improved yields and a wide range of functional group tolerance are some of the important features of the developed protocol.
Zirconium-catalyzed direct amide bond formation between carboxylic esters and amines
Lenstra, Danny C.,Nguyen, D. Thao,Mecinovi?, Jasmin
, p. 5547 - 5553 (2015/08/03)
Development of catalytic amide bond formation reactions from readily available starting materials remains a challenging task for modern organic chemistry. Herein, we report that unactivated carboxylic esters and amines react in the presence of 10 mol % of zirconocene dichloride (Cp2ZrCl2) in toluene at 110 °C to afford amides in very good to excellent conversions. The Zr-catalyzed reaction is amenable for the amidation of aliphatic and aromatic carboxylic esters with primary and secondary amines. The reaction proceeds with almost complete retention of configuration for chiral esters and chiral amines.
Chemoselective calcium-catalysed direct amidation of carboxylic esters
Nguyen, D. Thao,Lenstra, Danny C.,Mecinovi?, Jasmin
, p. 77658 - 77661 (2015/09/28)
Unactivated carboxylic esters and primary amines undergo calcium-catalysed direct amide bond formation in excellent yields under homogeneous conditions in toluene. This green and mild reaction proceeds chemoselectively with esters, whereas related carboxylic acids and amides remain unreactive.
Direct, rapid, solvent-free conversion of unactivated esters to amides using lithium hydroxide as a catalyst
Miller, Shelli A.,Leadbeater, Nicholas E.
, p. 93248 - 93251 (2015/11/17)
A simple, solvent-free methodology is reported for the direct conversion of esters to amides using lithium hydroxide as a catalyst. The approach allows for the preparation of a range of amide products as well as being applicable to the ring-opening of a representative lactone.
Catalyst and solvent-free amidation of inactive esters of N-protected amino acids
Nadimpally, Krishna Chaitanya,Thalluri, Kishore,Palakurthy, Nani Babu,Saha, Abhijit,Mandal, Bhubaneswar
, p. 2579 - 2582 (2011/06/21)
A catalyst free procedure for the preparation of amides from inactive esters of N-protected amino acids and various amines is demonstrated under mild reaction conditions. Our effort to recover excess amine and generated alcohol is an approach towards environment friendly and cost effective synthesis under easy operational conditions.
Catalytic ester-amide exchange using group (IV) metal alkoxide-activator complexes
Han, Chong,Lee, Jonathan P.,Lobkovsky, Emil,Porco Jr., John A.
, p. 10039 - 10044 (2007/10/03)
A process for preparation of amides from unactivated esters and amines has been developed using a catalytic system comprised of group (IV) metal alkoxides in conjunction with additives including 1-hydroxy-7-azabenzotriazole (HOAt). In general, ester-amide exchange proceeds using a variety of structurally diverse esters and amines without azeotropic reflux to remove the alcohol byproduct. Initial mechanistic studies on the Zr(Ot-Bu)4-HOAt system revealed that the active catalyst is a novel, dimeric zirconium complex as determined by X-ray crystallography.
Synthesis of 2-Amino-4-pyrimidinones from Resin-Bound Guanidines Prepared Using Bis(allyloxycarbonyl)-Protected Triflylguanidine
Zapf, Christoph W.,Goodman, Murray
, p. 10092 - 10097 (2007/10/03)
We have synthesized novel heterocyclic compounds from resin-bound guanidines. For this purpose, an amine immobilized on a solid support was acylated with protected amino acids. Following the deprotection, the liberated amines were guanidinylated utilizing a new member of the family of diurethane-protected triflyl guanidine reagents, N,N′ -bis(allyloxycarbonyl)-N′-triflylguanidine. The deprotected guanidines were subsequently regioselectively cyclized with β-keto esters yielding novel compounds containing heterocyclic structures in high purities.
