Studies on the Biosynthesis of Spirostaphylotrichin A

Abstract

Incorporation of 14C‐labelled acetate and amino acids as well as of [1‐13C]‐, [2‐13C]‐, and [1,2‐13C2] acetate, L‐[methyl13C] methionine, [2,3‐13C2] succinate, and L‐[2,3‐13C2] aspartate into spirostaphylotrichin A (1) by Staphylotrichum coccosporum demonstrates that the building blocks of 1 are 5 units of acetate/malonate, 1 unit of methionine, and a C4‐dicarboxylic acid. The latter is most likely aspartate and derived from the citric‐acid cycle. Using [2‐13C, 2‐2H3] acetate as a precursor, the starter unit of the polyketide chain was identified.

Chemistry and biology of non-tetramic γ-hydroxy-γ-lactams and γ-alkylidene-γ-lactams from natural sources

“…21 The hemisynthesis of synerazol and pseurotin E from pseurotin A has been reported and enabled the determination of the absolute stereochemistry of pseurotin E. 22 FD-838 (22) has been isolated from an Aspergillus strain and features an additional furan ring on the side chain. 23 Spirostaphylotrichin A ( 23) and congeners constitute another group of fungal spiro derivatives with a 6-membered carbocycle, isolated from Staphylotrichum coccosporum 24 and Curvularia pallescens. 25 (AE)-Pandamarine 24 is a racemic plantderived alkaloid with a spirolactam functionality isolated from Pandanus amaryllifolius, 26 which might be biosynthesized by the intramolecular 6-endo-addition of an amine to a 5-alkylidene-3-pyrrolin-2-one.…”

“…A model for the synthesis of pandamarine (24) has been developed, using N-Boc-3-methyl-2-trimethylsilyloxypyrrole 167 synthesized in four steps from the lactam 162 (Scheme 37). The oxidative 5-endo cyclization of enamides (189) has been performed in the presence of ceric ammonium nitrate 104 or manganese(III) triacetate (Scheme 41).…”

Biosynthesis and biogenetic interrelationships of metabolites of the fungus Arthropsistruncata

“…In the 2D-INADEQUATE spectra of 6 the signal of C4 is correlated not only to the signal of C3 but also to C5 and C9. This suggests that a significant number of molecules of arthropsadiol A (1) have multiple incorporation of sodium [1,[2][3][4][5][6][7][8][9][10][11][12][13] Cz]acetate at C3-C4, C5-C6, and C9-C10. Assuming that Jcc between C4 and C9 is approximately 35-40 Hz, then incorporation of sodium [I ,2-13~,]acetate at C3-C4, C5-C6, and C9-C10 would result in a ddd of satellite peaks due to coupling of C4 to C3, C5, and C9.…”

The biosynthesis of plant alkaloids and nitrogenous microbial metabolites

“…Further evidence pertaining to this comes from an experiment with the homocysteinyl tripeptide (124).97 It gave, instead of bicyclic lactams, the epimeric lactams (126), the formation of which is rationalized in a strictly similar way (Scheme 9) to that for (123) (Scheme 8). Two further points: the hydroxy group in (126) originates, in part at least, from aerial oxygen; results of an experiment with (125) show that reaction at the carbon next to the sulphur occurs with ca. 80% stereospecificity; (127) gave two epimeric alcohols strictly analogous to (126).…”