Carbon-13 as a biosynthetic tool. II. Carbon-13 magnetic resonance spectroscopy and the biosynthesis of streptovaricin

Biosynthesis of 3,5-AHBA-derived natural products

“…91,92 Streptovaricin biosynthesis has only been studied by feeding experiments with isotope-labeled putative precursors. 93,94 The incorporation of [carboxy-l4 C]AHBA, albeit in low efficiency, clearly proved that the aromatic chromophore of streptovaricins was derived from AHBA. 93,94 Furthermore, [methyl- 14 C]methionine was efficiently incorporated into the C-methyl groups at C-3 of the naphthalenic chromophore, and the methylenedioxy, and methoxy carbons (Fig.…”

Ansavaricins A–E: five new streptovaricin derivatives from Streptomyces sp. S012

“…S65 †). [22][23][24] The ROESY cross-peak observed from H-26 to H-24 proposed the relative conguration at the C-26 position, but the relative conguration of C-27 remained unknown for lack of related experimental data. Thus, 1 was deduced to be a new seco-streptovaricin, namely ansavaricin A (Fig.…”

“…S26 and S44 †). 19,22,23 The stereochemistry of C-26 was assumed to be the same as that of 1 on the basis of the ROESY cross-peak observed from H-21 to H-26. The relative congurations of C-7 and C-27 remained unresolved due to lack of ROESY correlations.…”

“…S65 †). [22][23][24]26 The ROESY conguration at the C-27 position, but the relative conguration of C-4 remained unknown. Thus, 5 was a new natural product of the undecaketide-type polyketide, for which we proposed the name ansavaricin E (Fig.…”

Studies directed towards the biosynthesis of the C7N-unit of rifamycin B: Incorporation of (14C(G))quinic acid and (1,2-13C2)glycerol.

“…The trace-element solution was added to the sterile fermentation mediumusing a sterile filter. Racemic Diethyl 2-Acetoxy-[l ,2-1 3C2]malonate (12) To a solution of ll (762mg, 4.80mmol) in 15ml abs benzene, 3.4g Pb(OAc)4 (ca. 1.5% AcOH; 6.52 mmol) were added under a steady stream of argon.…”