Two ambuic acid dimers derived from homo-endo Diels-Alder reaction from Pestalotiopsis versicolor

Abstract

Two new dimers of ambuic acid, pestaloversicoloric acids A (1) and B (2), and a known derivative, 13(S)-hydroxyambuic acid (3), were isolated from the static fermentation product of Pestalotiopsis versicolor. The structural identification was accomplished via analyses on the data of HR-MS, 1 D and 2 D NMR, and ECD. Different from the well-known exo-type dimer, torreyanic acid, compounds 1 and 2 represent the first example of endo-type product derived from the intermolecular Diels-Alder reaction of two molecules of ambuic acid derivative with the identical absolute stereochemistry.

 

Keywords:

• Ambuic acid
• Diels-Alder reaction
• endo-product
• Pestalotiopsis versicolor

Disclosure statement

No potential conflict of interests was reported by the author(s).

Additional information

Funding

This work was sponsored by the Natural Science Foundation of Liaoning Province, China [Grant number 2019-ZD-0452].