108-27-0Relevant articles and documents
Synthesis of γ-Lactams by Mild, o-Benzoquinone-Induced Oxidation of Pyrrolidines Containing Oxidation-Sensitive Functional Groups
Rong, Hao-Jie,Cheng, Yong-Feng,Liu, Fan-Fan,Ren, Shu-Jian,Qu, Jin
, p. 532 - 540 (2017)
The late-stage oxidation of substituted pyrrolidines offers good flexibility for the construction of γ-lactam libraries, and especially in recent years the methods for functionalization of pyrrolidine have been available. We reported a new strategy for oxidation of pyrrolidines to γ-lactams: reaction of pyrrolidine with an o-benzoquinone gives an N,O-acetal by direct oxidation of the α-C-H bond of the pyrrolidine ring, and then the N,O-acetal is further oxidized by the o-benzoquinone to the γ-lactam. Because the first oxidation occurs selectively at the α-C-H of the pyrrolidine ring, oxidation-sensitive functional groups (allyl-, vinyl-, hydroxyl-, and amino groups) on pyrrolidine ring are unaffected. The synthetic utility of this novel method was demonstrated by the facile syntheses of (S)-vigabatrin and two analogues.
Raney-Ni catalyzed conversion of levulinic acid to 5-methyl-2-pyrrolidone using ammonium formate as the H and N source
Amarasekara, Ananda S.,Lawrence, Yen Maroney
, p. 1832 - 1835 (2018)
Renewable biomass based levulinic acid was converted to 5-methyl-2-pyrrolidone in 94% yield by a Raney-Ni catalyzed process using ammonium formate in aqueous medium and heating at 180 °C for 3 h. The Raney-Ni could be reused for four catalytic cycles with about 10% loss in catalytic activity. In a similar reaction levulinic acid could be converted 1-substituted-5-methyl-2-pyrrolidones in 90–95% yield by using a mixture of formic acid and the corresponding primary amine.
Synthetic Utility of N-Benzoyloxyamides as an Alternative Precursor of Acylnitrenoids for γ-Lactam Formation
Huh, Soohee,Hong, Seung Youn,Chang, Sukbok
, p. 2808 - 2812 (2019)
Described herein is the development of a new entry of acylnitrenoid precursors for γ-lactam synthesis via an intramolecular C-H amidation reaction. Upon Ir catalysis, N-benzoyloxyamides serve as efficient substrates to afford 5-membered amides. Mechanistic studies revealed that the generation of a putative Ir-carbonylnitrenoid via N-O bond cleavage is facilitated by the chelation of countercations. This protocol offers a convenient and step-economic route to γ-lactams starting from the corresponding carboxylic acids.
Tropylium-promoted Ritter reactions
Doan, Son H.,Hussein, Mohanad A.,Nguyen, Thanh Vinh
supporting information, p. 8901 - 8904 (2021/09/10)
The Ritter reaction used to be one of the most powerful synthetic tools to functionalize alcohols and nitriles, providing valuableN-alkyl amide products. However, this reaction has not been frequently used in modern organic synthesis due to its employment of strongly acidic and harsh reaction conditions, which often lead to complicated side reactions. Herein, we report the development of a new method using salts of the tropylium ion to promote the Ritter reaction. This method works well on a range of alcohol and nitrile substrates, giving the corresponding products in good to excellent yields. This reaction protocol is amenable to microwave and continuous flow reactors, offering an attractive opportunity for further applications in organic synthesis.
Efficient palladium catalysis for the upgrading of itaconic and levulinic acid to 2-pyrrolidones followed by their vinylation into value-added monomers
Haus, Moritz O.,Hofmann, Jan P.,Konrad, Marc,Louven, Yannik,Palkovits, Regina
, p. 4532 - 4540 (2020/11/02)
The production of monomers from bio-based platform chemicals shows great potential to reduce the chemical industry's demand for fossil resources. We herein present a two-step approach, which yields N-vinyl-2-pyrrolidone monomers from bio-based carboxylic acids, such as itaconic and levulinic acid. A highly active, heterogeneous palladium catalyst facilitating the reductive amidation of itaconic acid (TOF = 950 molPyr·molPd-surface-1 h-1) as well as the reductive amination of levulinic acid (TOF = 4000 molPyr·molPd-surface-1 h-1) was designed. Especially the reductive amidation of itaconic acid to 3- and 4-methyl-2-pyrrolidone was found to be structure sensitive. A clear trend between Pd particle size and catalyst activity could be shown by the synthesis of Pd/C catalysts with varying Pd particle sizes. The vinylation of the synthesized methyl-2-pyrrolidones with acetylene was tested using common industrial conditions (10-18 bar acetylene, 150 °C, KOH catalyst, no solvent). Similar to the industrial vinylation of 2-pyrrolidone, good yields of up to 80% N-vinyl-methyl-2-pyrrolidone were received. Therefore, and due to the excellent maximum yield of methyl-2-pyrrolidones in reductive amidation (95 mol%), the envisioned process can be a promising drop-in technology, directly replacing fossil resources in the production of an established monomer class. This journal is
A Facile Direct Route to N-(Un)substituted Lactams by Cycloamination of Oxocarboxylic Acids without External Hydrogen
Li, Hu,Wu, Hongguo,Zhang, Heng,Su, Yaqiong,Yang, Song,Hensen, Emiel J. M.
, p. 3778 - 3784 (2019/08/07)
Lactams are privileged in bioactive natural products and pharmaceutical agents and widely featured in functional materials. This study presents a novel versatile approach to the direct synthesis of lactams from oxocarboxylic acids without catalyst or external hydrogen. The method involves the in situ release of formic acid from formamides induced by water to facilitate efficient cycloamination. Water also suppresses the formation of byproducts. This unconventional pathway is elucidated by a combination of model experiments and density functional theory calculations, whereby cyclic imines (5-methyl-3,4-dihydro-2-pyrrolone and its tautomeric structures) are found to be favorable intermediates toward lactam formation, in contrast to the conventional approach encompassing cascade reductive amination and cyclization. This sustainable and simple protocol is broadly applicable for the efficient production of various N-unsubstituted and N-substituted lactams.
