761344-55-2Relevant academic research and scientific papers
Protein synthesis assisted by native chemical ligation at leucine
Harpaz, Ziv,Siman, Peter,Ajish Kumar,Brik, Ashraf
scheme or table, p. 1232-1235+1158 (2011/05/03)
(Chemical Equation Presented) Triggering leucine: A new ligation strategy of using β-mercaptoleucine coupled with desulfurization at leucine sites was developed, and its applicability in protein synthesis is presented. The efficiency of our Leu-NCL was examined in several model peptides and utilized for the first total synthesis of HIV-1 Tat protein.
Diastereo- and enantioselective hydrogenation of α-amino-β-keto ester hydrochlorides catalyzed by an iridium complex with MeO-BIPHEP and NaBArF: Catalytic cycle and five-membered chelation mechanism of asymmetric hydrogenation
Maeda, Tsukuru,Makino, Kazuishi,Iwasaki, Masamichi,Hamada, Yasumasa
experimental part, p. 11954 - 11962 (2011/01/12)
The development of Ir-catalyzed asymmetric hydrogenation of α-amino-β-keto ester hydrochlorides is described. This reaction proceeds through a dynamic kinetic resolution to produce anti-β-hydroxy- α-amino acid esters in a high diastereo- and enantioselective manner. Mechanistic studies have revealed that this unique asymmetric hydrogenation proceeds through reduction of the ketone moiety via the five-membered transition state involving the chelation between the oxygen of the ketone and the nitrogen of the amine function. The relationship studies between the hydrogen pressure and the stereoselectivity have disclosed two mechanisms dependent on hydrogen pressure. Under low hydrogen pressure (15 atm), the reaction rate proportionally increased with the hydrogen pressure. However, under the high hydrogen conditions, the reaction rate exponentially accelerated along with the increasing hydrogen pressure, which suggests the participation of two or more of hydrogen atoms. Apply some pressure: The Ir-catalyzed asymmetric hydrogenation of α-amino-β-keto ester hydrochlorides proceeds through a dynamic kinetic resolution to produce anti-β-hydroxy-α-amino acid esters in a high diastereo- and enantioselective manner (see scheme). Mechanistic studies revealed that this unique asymmetric hydrogenation proceeds through reduction of the ketone moiety via the five-membered transition state.
Diastereo- And enantioselective synthesis of β-Hydroxy-α-amino acids: Application to the synthesis of a key intermediate for lactacystin
Li, Qiong,Yang, Shao-Bo,Zhang, Zhihui,Li, Lei,Xu, Peng-Fei
supporting information; experimental part, p. 1627 - 1631 (2009/09/24)
The development of a highly efficient and stereoselective methodology for the preparation of β-hydroxy-α- amino acids is described. Nucleophilic addition of enolates of tricyclic iminolactones 1a and 1b to aldehydes in the presence of 6 equiv of lithium chloride in THF at -78 °C leads to aldol adducts in good yield (63-86%) and high diastereoselectivity (up to >25:1 dr). Subsequently, hydrolysis of the aldol adducts under acidic conditions leads to the corresponding β-hydroxy-a-amino acids in good yields (up to 83%) and excellent enantiomeric excesses (99% ee) with good recovery yields of the chiral auxiliaries 6 and 7. This methodology was applied to the facile synthesis of the key intermediate for lactacystin along with several isomers.
A short, stereocontrolled, and practical synthesis of α-methylomuralide, a potent inhibitor of proteasome function
Saravanan,Corey
, p. 2760 - 2764 (2007/10/03)
An efficient and practical synthesis of α-methylomuralide (3), a selective inhibitor of proteasomes, has been developed as outlined in Scheme 1. Among the advantages of this route of synthesis over previously described approaches are (1) ease of scale-up
Total synthesis of (+)-lactacystin
Panek, James S.,Masse, Craig E.
, p. 1093 - 1095 (2007/10/03)
A double stereodifferentiating crotylation between aldehyde 1 and silane (S)-2 to afford homoallylic alcohol 3 is the key diastereoselective step (anti:syn > 30:1) in an efficient asymmetric synthesis of (+)-lactacystin. This compound is a metabolite isol
An asymmetric total synthesis of sanjoinine G1
Laib, Taoues,Zhu, Jieping
, p. 83 - 86 (2007/10/03)
A convergent total synthesis of sanjoinine G1, a 14-membered cyclopeptide alkaloid was described. Formation of aryl-alkyl ether bond with concomitant construction of macrocycle by way of an intramolecular SNAr reaction was the key step in this synthesis.
Total synthesis of (+)-lactacystin
Nagamitsu, Tohru,Sunazuka, Toshiaki,Tanaka, Haruo,Omura, Satoshi,Sprengeler, Paul A.,Smith III, Amos B.
, p. 3584 - 3590 (2007/10/03)
A total synthesis of the novel neurotrophic agent (+)-lactacystin (1) has been achieved in 11 steps and 14% overall yield from (2R,3S)-3-hydroxyleucine [(+)-16]. The construction and bioassay of several active analogs are also described. A new asymmetric approach furnished the four stereoisomers of 3-hydroxyleucine, as required starting materials in high overall yield and enantiomeric purity.
Structure of Amino Acids Isolated from Hydrolyzed HV-Toxin M, a Host-soecific Toxin-related Compound Produced by Helminthosporium victoriae
Kono, Yoshiki,Kinoshita, Takeshi,Takeuchi, Setsuo,Daly, J. M.
, p. 505 - 512 (2007/10/02)
The chemistry of several of the specific toxins isolated from a culture medium of the phytopathogenic fungus Helminthosporium victoriae, a causal agent of Victoria blight disease of oat, was studied.The structures of the amino acid components of the isolated HV-toxin M were identified, and the absolute configurations of the asymmetric α-carbons were elucidated as (S) (I - V, Fig. 1), (S) for C-3 of 3-OH-leucine (II), (R) for C-3 of 3-OH-lysine (V) and (Z) for 3-chlorodehydroalanine (VII).The structure of the other toxin simultaneously isolated, HV-toxin H, was found to be identical with victorin C.
