172097-41-5Relevant articles and documents
Continuous flow synthesis of α-halo ketones: Essential building blocks of antiretroviral agents
Pinho, Vagner D.,Gutmann, Bernhard,Miranda, Leandro S. M.,De Souza, Rodrigo O. M. A.,Kappe, C. Oliver
supporting information, p. 1555 - 1562 (2014/03/21)
The development of a continuous flow process for the multistep synthesis of α-halo ketones starting from N-protected amino acids is described. The obtained α-halo ketones are chiral building blocks for the synthesis of HIV protease inhibitors, such as atazanavir and darunavir. The synthesis starts with the formation of a mixed anhydride in a first tubular reactor. The anhydride is subsequently combined with anhydrous diazomethane in a tube-in-tube reactor. The tube-in-tube reactor consists of an inner tube, made from a gas-permeable, hydrophobic material, enclosed in a thick-walled, impermeable outer tube. Diazomethane is generated in the inner tube in an aqueous medium, and anhydrous diazomethane subsequently diffuses through the permeable membrane into the outer chamber. The α-diazo ketone is produced from the mixed anhydride and diazomethane in the outer chamber, and the resulting diazo ketone is finally converted to the halo ketone with anhydrous ethereal hydrogen halide. This method eliminates the need to store, transport, or handle diazomethane and produces α-halo ketone building blocks in a multistep system without racemization in excellent yields. A fully continuous process allowed the synthesis of 1.84 g of α-chloro ketone from the respective N-protected amino acid within ～4.5 h (87% yield).
A one-pot procedure for the preparation of N-9-fluorenylmethyloxycarbonyl- α-amino diazoketones from α-amino acids
Siciliano, Carlo,De Marco, Rosaria,Guidi, Ludovica Evelin,Spinella, Mariagiovanna,Liguori, Angelo
, p. 10575 - 10582 (2013/02/22)
The study describes a new "one-pot" route to the synthesis of N-9-fluorenylmethyloxycarbonyl (Fmoc) α-amino diazoketones. The procedure was tested on a series of commercially available free or side-chain protected α-amino acids employed as precursors. The conversion into the title compounds was achieved by masking and activating the α-amino acids with a single reagent, namely, 9-fluorenylmethyl chloroformate (Fmoc-Cl). The resulting N-protected mixed anhydrides were reacted with diazomethane to lead to the α-amino diazoketones, which were isolated by flash column chromatography in very good to excellent overall yields. The versatility of the procedure was verified on lipophilic α-amino acids and further demonstrated by the preparation of N-Fmoc-α-amino diazoketones also from α-amino acids containing side-chain masking groups, which are orthogonal to the Fmoc one. The results confirmed that tert-butyloxycarbonyl (Boc), tert-butyl (tBu), and 2,2,4,6,7-pentamethyldihydrobenzofuran-5-sulfonyl (Pbf), three acid-labile protecting groups mostly adopted in the solution and solid-phase peptide synthesis, are compatible to the adopted reaction conditions. In all cases, the formation of the corresponding C-methyl ester of the starting amino acid was not observed. Moreover, the proposed method respects the chirality of the starting α-amino acids. No racemization occurred when the procedure was applied to the synthesis of the respective N-Fmoc-protected α-amino diazoketones from l-isoleucine and l-threonine and to the preparation of a diastereomeric pair of N-Fmoc-protected dipeptidyl diazoketones.
Ultrasound mediated synthesis of 2-amino-1,3-selenazoles derived from Fmoc/Boc/Z-α-amino acids
Lalithamba, Haraluru S.,Narendra,Naik, Shankar A.,Sureshbabu, Vommina V.
experimental part, p. 77 - 90 (2010/12/19)
A simple and efficient one-pot synthesis of Fmoc/Boc/Z-amino acid derived 2-amino-1,3-selenazoles by the condensation of Nα-urethane protected amino acid derived bromomethyl ketones with selenourea under the influence of ultrasound has been described. Insertion of 2-amino-1,3-selenazole moiety in the side chains of Asp and Glu has also been achieved following the similar protocol. ARKAT USA, Inc.
Homologation of α-amino acids to β-amino acids: 9-Fluorenylmethyl chloroformate as a carboxyl group activating agent for the synthesis of Nα-protected aminoacyldiazomethanes
Kantharaju,Suresh Babu, Vommina V.
, p. 2152 - 2158 (2007/10/03)
An efficient and stereospecific homologation of urethane-protected α-amino acids to β-amino acids by Arndt-Eistert approach using an equimolar mixture of Fmoc-/Boc-/Z-α-amino acid and 9-fluorenylmethyl chloroformate for the acylation of diazomethane synth
Conformationally homogeneous cyclic tetrapeptides: Useful new three-dimensional scaffolds
Glenn, Matthew P.,Kelso, Michael J.,Tyndall, Joel D. A.,Fairlie, David P.
, p. 640 - 641 (2007/10/03)
The most commonly recognized motifs in protein-protein interactions are γ and β turns, which are defined by three to four contiguous amino acids in a peptide sequence. Cyclic tetrapeptides thus represent minimalist turn mimetics, but their usefulness is c
Synthesis of β-amino acids: 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyl-uronium tetrafluoroborate (TBTU) for activation of Fmoc-/Boc-/Z-α-amino acids
Patil, Basanagoud S.,Vasanthakumar, Ganga-Ramu,Suresh Babu
, p. 3089 - 3096 (2007/10/03)
A new and efficient method for the homologation of urethane protected α-amino acids to its β-homomers by the Arndt-Eistert method using TBTU as a coupling agent is described. Several Fmoc-/Boc-/Z-protected α-amino diazoketone derivatives have been obtaine
Synthesis of Fmoc-/Boc-/Z-β-amino acids via Arndt-Eistert homologation of Fmoc-/Boc-/Z-α-amino acids employing BOP and PyBOP
Vasanthakumar,Babu, V. V. Suresh
, p. 1691 - 1695 (2007/10/03)
A simple and efficient protocol for Arndt-Eistert chain homologation of Fmoc-/Boc-/Z-α-amino acids using BOP or PyBOP as a coupling agent to the corresponding β-amino acids, synthesizing the key intermediate α-diazoketones as crystalline solids in good yield is described.
Syntheses and CD-spectroscopic investigations of longer-chain β-peptides: Preparation by solid-phase couplings of single amino acids, dipeptides, and tripeptides
Arvidsson, Per I.,Frackenpohl, Jens,Seebach, Dieter
, p. 1522 - 1553 (2007/10/03)
The synthesis and CD-spectroscopic analysis of eleven water-soluble β-peptides composed of all-β3 or alternating β2- and β3-amino acids is described. Different approaches for the efficient syntheses of longer-chain β-pepti
A convenient method for the synthesis of β-amino acids via the Arndt-Eistert approach using p-toluenesulphonyl chloride as a carboxylic group activating agent
Vasanthakumar, Ganga-Ramu,Suresh Babu, Vommina V.
, p. 651 - 657 (2007/10/03)
A simple method for the synthesis of Z-/Boc-/Fmoc-protected β-amino acids by the Arndt-Eistert approach employing p-toluenesulphonyl chloride for the activation of the carboxyl group of Nα-protected amino acid is described. The method is rapid and gave good yields with opitical purity.
Peptide folding induces high and selective affinity of a linear and small β-peptide to the human somatostatin receptor 4
Gademann,Kimmerlin,Hoyer,Seebach
, p. 2460 - 2468 (2007/10/03)
β-Peptides with side chains in the 2- and 3-positions on neighboring residues (of (S) configuration) are known to fold and form a turn (similar to an α-peptidic β-turn). Thus, we have synthesized an appropriately substituted β-tetrapeptide derivative to mimic the hormone somatostatin in its binding to the human receptors hsst1-5, which is known to rest upon a turn containing the amino acid residues Thr, Lys, Trp, and Phe. The N-acetyl-peptide amide Acβ3-HThr-β2-HLys-β3 -HTrp-β3-HPhe-NH2 (1) indeed shows all characteristics of the targeted turnmimic: Lys CH2 groups are in the shielding cone of the Trp indole ring (by NMR analysis, Figure 2) and there is high and specific nanomolar affinity for hsst4 receptor (Table 1). In contrast, the isomer 2 bearing the Lys side chain in 3-, rather than in the 2-position, has a 1000-fold smaller affinity to hsst4. The syntheses of the required Fmoc-protected β-amino acids (8-11, 17) are described (Schemes 1-3). Coupling of the β-amino acids was achieved by the manual solid-phase technique, on Rink resin.
