5468-52-0Relevant articles and documents
Asymmetric Aza-Diels-Alder Reactions of in Situ Generated β,β-Disubstituted α,β-Unsaturated N-H Ketimines Catalyzed by Chiral Phosphoric Acids
He, Shunlong,Gu, Huanchao,He, Yu-Peng,Yang, Xiaoyu
supporting information, p. 5633 - 5639 (2020/07/14)
A novel asymmetric synthesis of dihydropyridinones with vicinal quaternary stereocenters has been realized by asymmetric aza-Diels-Alder reactions of 3-amido allylic alcohols with oxazolones enabled by chiral phosphoric acid catalysis. A series of aryl/alkyl- and alkyl/alkyl-disubstituted 3-amido allylic tertiary alcohols and 4-substituted oxazolones could be well tolerated in these reactions, producing dihydropyridinones with excellent diastereoselectivities and high enantioselectivities. Mechanistic study and control experiments were performed to shed light on the reaction mechanism, in which a configurationally defined β,β-disubstituted α,β-unsaturated N-H ketimine was proposed as the key intermediate.
Bifunctional squaramide-catalyzed synthesis of chiral dihydrocoumarins via ortho-quinone methides generated from 2-(1-tosylalkyl)phenols
Zhou, Ji,Wang, Mao-Lin,Gao, Xiang,Jiang, Guo-Fang,Zhou, Yong-Gui
supporting information, p. 3531 - 3534 (2017/03/30)
A bifunctional squaramide-catalyzed reaction of azlactones with o-quinone methides in situ generated from 2-(1-tosylalkyl)-phenols has been successfully developed under basic conditions, providing an efficient and mild access to chiral dihydrocoumarins bearing adjacent tertiary and quaternary stereogenic centers in high yields with excellent diastereo- and enantioselectivities.
Palladium-Catalyzed Ortho-Alkoxylation of N-Benzoyl α-Amino Acid Derivatives at Room Temperature
Li, Shuangjie,Zhu, Wei,Gao, Feng,Li, Chunpu,Wang, Jiang,Liu, Hong
, p. 126 - 134 (2017/04/26)
An efficient palladium-catalyzed ortho-alkoxylation of N-benzoyl α-amino acid derivatives at room temperature has been explored. This novel transformation, using amino acids as directing groups, Pd(OAc)2 as catalyst, alcohols as the alkoxylation reagents, and PhI(OAc)2 as the oxidant, showed wide generality, good functional tolerance, and high monoselectivity and regioselectivity.
Regiodivergent Enantioselective γ-Additions of Oxazolones to 2,3-Butadienoates Catalyzed by Phosphines: Synthesis of α,α-Disubstituted α-Amino Acids and N,O-Acetal Derivatives
Wang, Tianli,Yu, Zhaoyuan,Hoon, Ding Long,Phee, Claire Yan,Lan, Yu,Lu, Yixin
supporting information, p. 265 - 271 (2016/01/25)
Phosphine-catalyzed regiodivergent enantioselective C-2- and C-4-selective γ-additions of oxazolones to 2,3-butadienoates have been developed. The C-4-selective γ-addition of oxazolones occurred in a highly enantioselective manner when 2-aryl-4-alkyloxazol-5-(4H)-ones were employed as pronucleophiles. With the employment of 2-alkyl-4-aryloxazol-5-(4H)-ones as the donor, C-2-selective γ-addition of oxazolones took place in a highly enantioselective manner. The C-4-selective adducts provided rapid access to optically enriched α,α-disubstituted α-amino acid derivatives, and the C-2-selective products led to facile synthesis of chiral N,O-acetals and γ-lactols. Theoretical studies via DFT calculations suggested that the origin of the observed regioselectivity was due to the distortion energy that resulted from the interaction between the nucleophilic oxazolide and the electrophilic phosphonium intermediate.
Asymmetric palladium(II)-catalyzed cascade reaction giving quaternary amino succinimides by 1,4-addition and a nef-type reaction
Weber, Manuel,Frey, Wolfgang,Peters, Rene
supporting information, p. 13223 - 13227 (2014/01/06)
Simple starting materials, high-value products: A dinuclear ferrocene-based PdII complex transforms mixtures of racemic N-benzoyl α-amino acids, nitroolefins, acetic anhydride, and manganese acetate into biologically interesting quaternary amin
Polyclonal antibodies: A cheap and efficient tool for screening of enantioselective catalysts
MacOvei, Cristian,Vicennati, Paola,Quinton, Julia,Nevers, Marie-Claire,Volland, Herve,Creminon, Christophe,Taran, Frederic
supporting information; experimental part, p. 4411 - 4413 (2012/05/20)
Enantioselective polyclonal antibodies have been produced and characterized to develop a high-throughput screening method for lipase activity fingerprinting, with a view to the enantioselective hydrolysis of azlactones.
Bispalladacycle-catalyzed Michael addition of in situ formed azlactones to enones
Weber, Manuel,Jautze, Sascha,Frey, Wolfgang,Peters, René
supporting information, p. 14792 - 14804 (2013/01/15)
The development and further evolution of the first catalytic asymmetric conjugate additions of azlactones as activated amino acid derivatives to enones is described. Whereas the first-generation approach started from isolated azlactones, in the second-generation approach the azlactones could be generated in situ starting from racemic N-benzoylated amino acids. The third evolution stage could make use of racemic unprotected α-amino acids to directly form highly enantioenriched and diastereomerically pure masked quaternary amino acid products bearing an additional tertiary stereocenter. The step-economic transformations were accomplished by cooperative activation by using a robust planar chiral bis-Pd catalyst, a Br?nsted acid (HOAc or BzOH; Ac=acetyl, Bz=benzoyl), and a Br?nsted base (NaOAc). In particular the second- and third-generation approaches provide a rapid and divergent access to biologically interesting unnatural quaternary amino acid derivatives from inexpensive bulk chemicals. In that way highly enantioenriched acyclic α-amino acids, α-alkyl proline, and α-alkyl pyroglutamic acid derivatives could be prepared in diastereomerically pure form. In addition, a unique way is presented to prepare diastereomerically pure bicyclic dipeptides in just two steps from unprotected tertiary α-amino acids. Flourishing step economy: The evolution of the catalytic asymmetric addition of azlactones to enones is described. The first-generation approach started from isolated azlactones. In the second-generation approach azlactones could be generated in situ from racemic N-benzoylated amino acids. The third evolution stage could directly use racemic unprotected α-amino acids to form a large number of highly enantioenriched quaternary amino acids derivatives (see figure). Copyright
Bispalladacycle-catalyzed bronsted acid/base-promoted asymmetric tandem azlactone formation-michael addition
Weber, Manuel,Jautze, Sascha,Frey, Wolfgang,Peters, Rene
supporting information; experimental part, p. 12222 - 12225 (2010/11/03)
Cooperative activation by a soft bimetallic catalyst, a hard Bronsted acid, and a hard Bronsted base has allowed the formation of highly enantioenriched, diastereomerically pure masked α-amino acids with adjacent quaternary and tertiary stereocenters in a single reaction starting from racemic N-benzoylated amino acids. The products can, for example, be used to prepare bicyclic dipeptides.
PREPARATION OF (S)-2-AMINOBUTYRIC ACID
-
Page/Page column 7-8, (2010/04/03)
Processes for the preparation of (S)-2-aminobutyric acid, embodiments including selective hydrolysis of racemic N-protected-2-aminobutyric acid using an acylase enzyme, such as one derived from Thermococcus litorolis or Aspergillus melleus.
1-Acyldeoxyvasicinone salts as effective intermediate C- and N-acylating agents for alkaloids and amino acids
Shakhidoyatov,Genjemuratova,Oripov
, p. 718 - 723 (2008/02/08)
The reaction of deoxyvasicinone with acid chlorides of aliphatic (acetylbromide) and aromatic (benzoyl-, o-, p-methoxy-, p-nitrobenzoylchlorides) acids was studied. It was shown that 1-deoxyvasicinone salts were formed at room temperature; α-aroyloxymethylidenedeoxyvasicinones, in the presence of triethylamine at 80-85°C. It was found that acid chlorides cause 1-acyldeoxyvasicinone salts to transform into α-hydroxy-or α-aroyloxyarylidenedeoxyvasicinones, which indirectly confirmed their acylating properties. It was found that 1-acyldeoxyvasicinone salts were effective acylating agents for alkaloids (cytisine, 1,2-dihydrodeoxyvasicinone) and amino acids (glycine, β-alanine, α-aminobutyric acid) and can be used to acylate primary and secondary aliphatic and heterocyclic amines.
