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Polyketide macrocycles synthesis

A multifunctional biosynthetic machinery mediates the synthesis of these complex natural products from acetyl- and propionyl-coenzyme A [3). In the case of type I polyketide-synthases, the )8-oxo-esters made by polycondcnsa-tion steps are modified for example by reduction or dehydration after the chain elongation. Additional specific enzymatic transformations, e.g. oxidations and glycosylations, usually take place after the decoupling at the completed macrocyclic ring framework [1,3],... [Pg.343]

Swinholide A is an interesting physiologically highly active marine metabolite with a macrocyclic diolide structure and a polyketide carbon skeleton. Recently the first total synthesis of 161 was reported by I. Paterson et al. (21). We focused on the synthesis of the tetrahydropyran part of the molecule as represented by compound 162. The particular feature of this ring is that it bears the largest substituent (at C-27) in an axial arrangement, as shown by the X-ray crystal structure of 161. [Pg.186]

The isolated TE domain from the tyrocidine (tyc) NRPS has recently been shown to catalyze the macrocyclization of unnatural substrates to generate a variety of cyclic peptides. In conjunction with standard solid-phase peptide synthesis, Walsh and coworkers demonstrated a broad substrate tolerance for peptidyl-N-acetylcysteamine thioesters by the tyrocidine TE [41,42], Cyclization of peptide analogs, where individual amino acids were replaced with ethylene glycol units, was observed with high efficiency. In addition, hydroxyacid starter units were readily cyclized by the isolated TE domain to form nonribosomal peptide-derived macrolactones. More recently, Walsh and coworkers have demonstrated effective cyclization of PEGA resin-bound peptide/polyketide hybrids by the tyrocidine TE domain [43], Utilization of a pantetheine mimic for covalent attachment of small molecules to the resin, serves as an appropriate recognition domain for the enzyme. As peptide macrocyclizations remain challenging in the absence of enzymatic assistance, this approach promises facile construction of previously unattainable structures. [Pg.527]

Still reported that triepoxide 12 was formed diastereoselectively from tri-ene 11 (dr=20 l.l, Scheme 9.1) [57, 58], Saponification followed by acid-induced cyclization gave 13, which served as a model substrate in studies towards the synthesis of the polyether antibiotic monensin B [57]. This example thus involves the use of macrocyclic stereocontrol (see Chapter 1) in the synthesis of polyketide antibiotics. [Pg.265]


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See also in sourсe #XX -- [ Pg.376 ]




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Macrocycles synthesis

Macrocyclic polyketide

Macrocyclic polyketide macrocyclization

Polyketide

Polyketides

Polyketides synthesis

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