5619-01-2Relevant articles and documents
Total synthesis of (-)-platensimycin by advancing oxocarbenium- and iminium-mediated catalytic methods
Eey, Stanley T.-C.,Lear, Martin J.
, p. 11556 - 11573 (2015/01/16)
(-)-Platensimycin is a potent inhibitor of fatty acid synthase that holds promise in the treatment of metabolic disorders (e.g., diabetes and "fatty liver") and pathogenic infections (e.g., those caused by drug-resistant bacteria). Herein, we describe its total synthesis through a four-step preparation of the aromatic amine fragment and an improved stereocontrolled assembly of the ketolide fragment, (-)-platensic acid. Key synthetic advances include 1) a modified Lieben haloform reaction to directly convert an aryl methyl ketone into its methyl ester within 30 seconds, 2) an experimentally improved dialkylation protocol to form platensic acid, 3) a sterically controlled chemo- and diastereoselective organocatalytic conjugate reduction of a spiro-cyclized cyclohexadienone by using the trifluoroacetic acid salt of α-amino di-tert-butyl malonate, 4) a tetrabutylammonium fluoride promoted spiro-alkylative para dearomatization of a free phenol to assemble the cagelike ketolide core with the moderate leaving-group ability of an early tosylate intermediate, and 5) a bismuth(III)-catalyzed Friedel-Crafts cyclization of a free lactol, with LiClO4 as an additive to liberate a more active oxocarbenium perchlorate species and suppress the Lewis basicity of the sulfonyloxy group. The longest linear sequence is 21 steps with an overall yield of 3.8% from commercially available eugenol. Relay tactics: The stereocontrolled assembly of the potent antibiotic (-)-platensimycin in 21 steps and 3.8% yield from eugenol is described (see scheme; TBAF: tetrabutylammonium fluoride; Ts: toluene-4-sulfonyl). Highlights are 1) a rapid oxidative esterification of an acyl aromatic, 2) a reliable dialkylation protocol to form platensic acid, 3) a π-facial conjugate reduction of a dienone, 4) a TBAF-promoted alkylative dearomatization of a free phenol, and 5) a Friedel-Crafts closure of a free lactol.
New synthetic routes to α-amino acids and γ-oxygenated α-amino acids. Reductive denitration and oxidative transformations of γ-nitro-α-amino acids
Crossley, Maxwell J.,Fung, Yik M.,Kyriakopoulos, Efstathia,Potter, Jeffrey J.
, p. 1123 - 1130 (2007/10/03)
Transformation of γ-nitro-α-amino acid derivatives into α-amino acids by reductive denitration, into the γ-oxo-α-amino acids by ozonolysis of the corresponding amino acid ester nitronate derivatives, and into γ-hydroxy-α-amino acid derivatives by subsequent reduction of the oxo functionality, can be achieved in good yields. As the γ-nitro-α-amino acid derivatives are prepared from N,O-protected dehydroalanines derivable from the corresponding alanine, serine and cysteine derivatives by specific routes, the overall procedures provide a means for selective conversion of these simple α-amino acids into more complex ones.
Composition containing a penem or carbapenem antibiotic
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, (2008/06/13)
Administration of an N-acylated amino acid in association with a penem or carbapenem antibiotic relieves or eliminates the renal problems associated with administration of the antibiotic alone. The amino acid derivative and antibiotic may be formulated together as a composition or administered separately, either simultaneously or sequentially. The composition may be prepared by simple mixing.
