20918-84-7Relevant academic research and scientific papers
Ultrasound-Promoted Enantioselective Decarboxylative Protonation of α-Aminomalonate Hemiesters by Chiral Squaramides: A Practical Approach to Both Enantiomers of α-Amino Esters
Some, Surajit,Bae, Han Yong,Kim, Mun Jong,Zhang, Yong Jian,Song, Choong Eui
, p. 4562 - 4565 (2017)
Herein, we report an ultrasound-promoted enantioselective decarboxylative protonation reaction of α-aminomalonate hemiesters 1 in the presence of chiral cinchona-derived squaramide Br?nsted bases under mild conditions, which afforded both the (S)- and (R)-enantiomers of α-amino acid derivatives 2 in excellent yields (> 90 %) and excellent enantioselectivities (up to 98 % ee).
Concise synthesis and applications of enantiopure spirobiphenoxasilin-diol and its related chiral ligands
Liu, Tao,Wang, Biqin,Wang, Peng,Wu, Yichen,Xu, Wen-Qiang,Yang, Lei
supporting information, p. 13365 - 13368 (2021/12/17)
The development of chiral architectures for chiral ligand and catalyst discovery is essential for asymmetric catalysis. Herein, we report the concise synthesis of a Si-centered spirocyclic skeleton, spirobiphenoxasilin-diol (SPOSiOL), and its derived chiral ligands. Using the chemical resolution method, the optical SPOSiOL could be obtained in high yield on a gram scale. Preliminary studies indicated that this ligand scaffold has great potential in transition metal-catalyzed asymmetric reactions. This finding further highlights that the Si-centered spirocyclic scaffolds are of great value in asymmetric catalysis. This journal is
New chiral ferrocene/indole-based diphosphine ligands for Rh-catalyzed asymmetric hydrogenation of functionalized olefins
Abbas, Zaheer,Ali, Aijaz,Hu, Xiang-Ping,Hu, Xin-Hu,Xu, You-Wei
, (2020/04/02)
Convenient synthesis of a new family of chiral ferrocene/indole-based diphosphine ligands, (Rc,Rp)-IndoFerroPhos (L), from (Sc,Rp)-PPFA and 2-(diphenylphosphino)indole has been described. These new ligands exhibited high efficiency in the Rh-catalyzed asymmetric hydrogenation of functionalized olefins including α-dehydroamino acid esters, α-enamides and dimethyl itaconate, in which up to >99% yield and 98% ee were achieved.
Topology-Based Functionalization of Robust Chiral Zr-Based Metal-Organic Frameworks for Catalytic Enantioselective Hydrogenation
Jiang, Hong,Zhang, Wenqiang,Kang, Xing,Cao, Ziping,Chen, Xu,Liu, Yan,Cui, Yong
supporting information, p. 9642 - 9652 (2020/07/02)
The design and development of robust and porous supported catalysts with high activity and selectivity is extremely significant but very challenging for eco-friendly synthesis of fine chemicals and pharmaceuticals. We report here the design and synthesis of highly stable chiral Zr(IV)-based MOFs with different topologies to support Ir complexes and demonstrate their network structures-dependent asymmetric catalytic performance. Guided by the modulated synthesis and isoreticular expansion strategy, five chiral Zr-MOFs with a flu or ith topology are constructed from enantiopure 1,1′-biphenol-derived tetracarboxylate linkers and Zr6, Zr9, or Zr12 clusters. The obtained MOFs all show high chemical stability in boiling water, strongly acidic, and weakly basic aqueous solutions. The two flu MOFs featuring the dihydroxyl groups of biphenol in open and large cages, after sequential postsynthetic modification with P(NMe2)3 and [Ir(COD)Cl]2, can be highly efficient and recyclable heterogeneous catalysts for hydrogenation of α-dehydroamino acid esters with up to 98% ee, whereas the three ith MOFs featuring the dihydroxyl groups in small cages cannot be installed with P(NMe2)3 to support the Ir complex. Incorporation of Ir-phosphorus catalysts into Zr-MOFs leads to great enhancement of their chemical stability, durability, and even stereoselectivity. This work therefore not only advances Zr-MOFs as stable supports for labile metal catalysts for heterogeneous asymmetric catalysis but also provides a new insight into how highly active chiral centers can result due to the framework topology.
Synthesis of constrained tetracyclic peptides by consecutive CEPS, CLIPS, and oxime ligation
Streefkerk, Dieuwertje E.,Schmidt, Marcel,Ippel, Johannes H.,Hackeng, Tilman M.,Nuijens, Timo,Timmerman, Peter,Van Maarseveen, Jan H.
supporting information, p. 2095 - 2100 (2019/04/11)
In Nature, multicyclic peptides constitute a versatile molecule class with various biological functions. For their pharmaceutical exploitation, chemical methodologies that enable selective consecutive macrocyclizations are required. We disclose a combination of enzymatic macrocyclization, CLIPS alkylation, and oxime ligation to prepare tetracyclic peptides. Five new small molecular scaffolds and differently sized model peptides featuring noncanonical amino acids were synthesized. Enzymatic macrocyclization, followed by one-pot scaffold-assisted cyclizations, yielded 21 tetracyclic peptides in a facile and robust manner.
Thioamide-substituted cinchona alkaloids as efficient organocatalysts for asymmetric decarboxylative reactions of MAHOs
Singjunla, Yuttapong,Pigeaux, Morgane,Laporte, Romain,Baudoux, Jér?me,Rouden, Jacques
supporting information, p. 4319 - 4320 (2018/08/24)
A new class of thioamide-substituted cinchona derivatives is reported. A convergent and practical approach was developed to insert the thioamide functional group onto the cinchonidine from readily available dithioesters. These organocatalysts were effective in asymmetric decarboxylative Mannich and protonation reactions of α-amido-substituted malonic acid half oxyesters (MAHOs), affording α,β- and α-amino acid derivatives, respectively, in good yields and stereoselectivities.
Towards a universal organocatalyst for the synthesis of enantioenriched phenylalanine derivatives by enantioselective decarboxylative protonation
Pigeaux, Morgane,Laporte, Romain,Harrowven, David C.,Baudoux, Jér?me,Rouden, Jacques
supporting information, p. 4599 - 4603 (2016/09/23)
Access to enantioenriched non-proteogenic phenylalanine derivatives is described using the enantioselective decarboxylative protonation reaction of amidohemimalonate esters catalysed by various cinchona-based compounds. This study compares the catalytic efficiency as well as the enantioselectivity induced by three types of common organocatalysts, namely thioureas, squaramides and bis-cinchona squaramides. One of the main outcome of this work is the observation of a significant influence of the N-protecting group of the hemimalonate on its interaction with the catalyst. This methodology carried out under mild conditions exhibits good substrate scope and functional group tolerance. A substoichiometric amount of catalyst can also be used in certain cases while affording good yields and selectivities.
Urea treated subtilisin as a biocatalyst for transformations in organic solvents
Mukherjee, Joyeeta,Mishra, Prasant,Gupta, Munishwar N.
, p. 1976 - 1981 (2015/03/30)
Abstract Subtilisin lyophilized from its solution in aqueous buffer in the presence of 6 M urea showed up to 50-fold increase (as compared to lyophilized subtilisin not subjected to urea treatment) in its initial rate of a transesterification reaction in anhydrous n-hexane. The lyophilization time controlling the extent of 'drying' was an important parameter. The urea treated subtilisin had five times shorter half life during heating at 100 C in hexane. The change in conformation was also reflected in its 92-fold higher activity at 15 C as compared to merely 28-fold higher activity at 45 C. The comparative enantioselectivity of urea treated subtilisin during kinetic resolution of 1-phenylethanol was expectedly lower. Its enantioselectivity during kinetic resolution of a natural substrate N-acetyl-(R,S)-phenylalanine ethyl ester in hexane was higher. Urea treated subtilisin also showed higher catalytic promiscuity during an aldol condensation. CD studies in both far UV and near UV region were also carried out to compare the two structures.
An eco-benign and highly efficient procedure for N-acylation catalyzed by heteropolyanion-based ionic liquids using carboxylic acid under solvent-free conditions
Chen, Zhikai,Fu, Renzhong,Chai, Wen,Zheng, Hao,Sun, Lin,Lu, Qiang,Yuan, Rongxin
, p. 2237 - 2245 (2014/03/21)
An eco-benign and highly efficient route for N-acylation of amines has been developed by treating amines with corresponding carboxylic acids in the presence of 2 mol % of heteropolyanion-based ionic liquids as catalysts under solvent-free conditions. This practical reaction could tolerate a wide range of substrates. Thus, various N-acylation products including N-acyl α-amino acid derivatives were obtained in moderate to excellent yields at 70 C to 120 C. Moreover, recycling studies revealed that heteropolyanion-based ionic liquids were easily reusable for this N-acylation. This method provides a green and much improved protocol over the existing methods.
Self-disproportionation of enantiomers of non-racemic chiral amine derivatives through achiral chromatography
Nakamura, Tsuyoshi,Tateishi, Kaori,Tsukagoshi, Shiori,Hashimoto, Saori,Watanabe, Shotaro,Soloshonok, Vadim A.,Ace?a, José Luis,Kitagawa, Osamu
experimental part, p. 4013 - 4017 (2012/07/14)
Efficient self-disproportionation of enantiomers of several non-racemic chiral amines was achieved through conversion to N-acetamides and subsequent MPLC using an achiral column. The MPLC of these non-racemic N-acetamide derivatives gave the chart having a clear boundary between two fractions. Thus, in the less polar fraction, remarkable enantiomer enrichment was observed (>99%ee), while the ee of more polar fraction was considerably reduced. The magnitude of the enantiomer enrichments and depletions strongly depended on substituent on the amino group.
