Cytospolides A–E, New Nonanolides from an Endophytic Fungus, Cytospora sp.

Abstract

Cytospolides A-E (1-5), five new nonanolides with an unprecedented 15-carbon skeleton with the unique chemical feature of a C-2 methyl group, were isolated from the endophytic fungus Cytospora sp. The structures were elucidated by spectroscopic analysis, chemical interconversion, and single-crystal XRD. The solution and solid state conformers were compared by experimental methods (X-ray, NMR) and solvent and gas phase DFT calculations. The absolute configurations were assigned by time dependent (TD)-DFT calculations of CD spectra, including solution and solid state CD/

Current Applications of Suzuki–Miyaura Coupling Reaction in The Total Synthesis of Natural Products: An update

“…Nonanolides cytospolides A‐E are bioactive compounds that were intially extracted from endophytic fungus Cytospora sp. and Ilex canariensis Poir . The total synthesis of Cytospolide E 544 was accomplished starting from easily accessible enol 545 and enantiopure primary alcohol 547 , which intially are converted into boronate 546 and E ‐vinylic bromide 548 respectively in several steps.…”

Applications of Mitsunobu Reaction in total synthesis of natural products

“…Zhang et al . in 2011 initially isolated a family of nonanolides, so‐called cytospolides, by simple extraction by acetone from Cytospora sp. Which is an endophytic fungus from an ever green shrub (Ilex canariensis) found on the island of Gomera, Spain several molecules present in this family exhibited cytotoxic potency to diverse human carcinogenic cell lines.…”

“…Notably, the presence of a further –CH 3 group situated at the C‐2 in 136 is exclusive among the members of the cytospolide family since it is absent in other nonanolide families . It is clear that the stereochemistry of the C‐2 –CH 3 group plays an important role in the biological behavior of the molecules in the cytospolides family …”

Achaetolide-II isolated from Helminthosporium velutinum TS28

“…5 Thus, they have become attractive synthetic targets for organic chemists. [6][7][8] We have recently isolated achaetolide (1) 9 from Ophiobolus sp.…”

“…14 The structural studies involve configurational determination of asymmetric centers in the side chain based on NOE experiments, theoretical chemical shift computations, and chemical derivatization. The absolute configuration was investigated by means of an electronic circular dichroism (ECD) exciton chirality method after conversion into the 6,7-O-dibenzoate (5). Degradation of 2 and the following chemical transformations were performed to verify the stereochemical conclusion.…”