41445-88-9Relevant academic research and scientific papers
Lewis acid- and cationic lithium-mediated diastereoselective aldol-type reaction based on a double chiral recognition manner for the asymmetric synthesis of α-substituted serines
Sano,Liu,Takebayashi,Kobayashi,Tabata,Shiro,Nagao
, p. 4101 - 4104 (1995)
Diastereoselective aldol-type reaction of ethyl (5R or 5S)-3,6-diethoxy-2,5-dihydro-5-isopropyl-2-pyrazinecarboxylate (5) with chiral aldehyde 7 was investigated by using Sn(OSO2CF3)2-N-ethylpiperizine, MgBr2-Et
Synthesis and characterization of chiral di(N-protected-α-amino) diazo-β-diketones from α-diazoketones and imidazolides derived from amino acids
Saraireh, Ibrahim A.M.
supporting information; experimental part, p. 2023 - 2025 (2012/07/17)
Di(N-protected-α-amino)diazo-β-diketones were prepared by the reaction of activated N-protected-α-amino acids (imidazolides) with α-diazoketones, derived from natural amino acids, in the presence of lithium diisopropylamide in tetrahydrofuran as the solvent at -78 °C.
HETEROCYCLIC UREA DERIVATIVES AND METHODS OF USE THEREOF
-
, (2010/12/29)
Compounds of formula (IA) and their pharmaceutically acceptable salts are described. Processes for their preparation, pharmaceutical compositions containing them, their use as medicaments and their use in the treatment of bacterial infections are also described.
Employing the structural diversity of nature: Development of modular dipeptide-analogue ligands for ruthenium-catalyzed enantioselective transfer hydrogenation of ketones
Pastor, Isidro M.,Vaestilae, Patrik,Adolfsson, Hans
, p. 4031 - 4045 (2007/10/03)
A library of novel dipeptideanalogue ligands based on the combination of tert-butoxycarbonyl(N-Boc)-protected a-amino acids and chiral vicinal amino alcohols were prepared. These highly modular ligands were combined with [{RuCl2(p-cymene)}2 and the resulting metal complexes were screened as catalysts for the enantioselective reduction of acetophenone under transfer hydrogenation conditions using 2-propanol as the hydrogen donor. Excellent enantioselectivity of 1-phenylethanol (up to 98% ee) was achieved with several of the novel catalysts. Although most of the ligands contained two stereocenters, it was demonstrated that the absolute configuration of the product alcohol was determined by the configuration of the amino acid part of the ligand. Employing ligands based on L-amino acids generated S-configured products, and catalysts based on Damino acids favored the formation of the R-configured alcohol. The combination N-Boc-L-alanine and (R)-phenylglycinol (Boc-L-Ab) or its enantiomer (N-Boc-D-alanine and (S)-phenylglycinol, Boc-D-Aa) proved to be the best ligands for the reduction process. Transfer hydrogenation of a number of aryl alkyl ketones were evaluated and excellent enantioselectivity, up to 96 % ee, was obtained.
Preparation and structure-activity relationship of novel P1/P1'- substituted cyclic urea-based human immunodeficiency virus type-1 protease inhibitors
Nugiel,Jacobs,Worley,Patel,Kaltenbach III,Meyer,Jadhav,De Lucca,Smyser,Klabe,Bacheler,Rayner,Seitz
, p. 2156 - 2169 (2007/10/03)
A series of novel P1/P1'-substituted cyclic urea-based HIV-1 protease inhibitors was prepared. Three different synthetic schemes were used to assemble these compounds. The first approach uses amino acid-based starting materials and was originally used to prepare DMP 323. The other two approaches use L-tartaric acid or L-mannitol as the starting material. The required four contiguous R,S,S,R centers of the cyclic urea scaffold are introduced using substrate control methodology. Each approach has specific advantages based on the desired P1/P1' substituent. Designing analogs based on the enzyme's natural substrates provided compounds with reduced activity. Attempts at exploiting hydrogen bond sites in the S1/S1' pocket, suggested by molecular modeling studies, were not fruitful. Several analogs had better binding affinity compared to our initial leads. Modulating the compound's physical properties led to a 10-fold improvement in translation resulting in better overall antiviral activity.
Total synthesis and assignment of configuration of lissoclinamide 7
Wipf, Peter,Fritch, Paul C.
, p. 12358 - 12367 (2007/10/03)
The first total synthesis of lissoclinamide 7, a 21-membered cyclopeptide isolated from Lissoclinum bistratum, was accomplished in 23 steps and 4.4% overall yield. The extraordinary configurational lability of the thiazoline segments was overcome by a novel strategy combining the use of the Burgess reagent for multiple simultaneous oxazoline and thiazoline formations and an efficient oxazoline → thiazoline heterocycle interconversion. In addition to the total synthesis, this work highlights the scope of alternative strategies toward Lissoclinum peptides and presents the preparation of analogues for SAR studies of the cytotoxic effects of this family of marine natural products.
Conformational Investigations of α,β-Dehydropeptides. I. Synthesis of Model Dipeptides
Pietrzynski, Grzegorz,Kubica, Zbigniew,Rzeszotarska, Barbara
, p. 363 - 370 (2007/10/02)
Three series of model dipeptides: Ac-Pro-X-NHMe, where X = L-, D- and Δ-Ala, L-, D- and (Z)-Δ-Phe and L-, D- and Δ-Val, designed for conformational investigation of α,β-dehydroamino acid effect on peptide chain β-turn have been synthesized.
