Cytochalasins from an Australian Marine Sediment-Derived Phomopsis sp (CMB-M0042F): Acid-Mediated Intramolecular Cycloadditions Enhance Chemical Diversity

TitleCytochalasins from an Australian Marine Sediment-Derived Phomopsis sp (CMB-M0042F): Acid-Mediated Intramolecular Cycloadditions Enhance Chemical Diversity
Publication TypeJournal Article
Year of Publication2017
AuthorsShang Z., Raju R., Salim A.A, Khalil Z.G, Capon R.J
JournalJournal of Organic Chemistry
Volume82
Pagination9704-9709
Date Published2017/09
Type of ArticleArticle
ISBN Number0022-3263
Accession NumberWOS:000411304500044
Abstract

Chemical analysis of an Australian coastal marine sediment-derived fungus, Phomopsis sp. (CMB-M0042F), yielded the known cytochalasins J (1) and H (2), together with five new analogues, cytochalasins J1-J3 (3-5) and H-1 and H-2 (6 and 7). Structures of 1-7 were assigned on the basis of detailed spectroscopic analysis, chemical interconversion, and biosynthetic and mechanistic considerations. Of note, 1 and 2 proved to be highly sensitive to acid mediated transformation, with 1 affording 3-5 and 2 affording 6 and 7. Whereas 1, 2, 4, and 5 were detected as natural products in crude culture extracts, 3, 6, and 7 were designated as acid-mediated handling artifacts. We propose novel stereo and regiospecific intramolecular cycloadditions, under tight functional group control, that facilitate selective conversion of 1 and 2 to the rare 5/6/6/7/5- and 5/6/5/8-fused heterocycles 5 and 7, respectively. Knowledge of acid sensitivity within the cytochalasin family provides a valuable cautionary lesson that has the potential to inform our analysis of past and future investigations into this structure class and inspire novel biomimetic transformations leading to new chemical diversity.

DOI10.1021/acs.joc.7b01793
Short TitleJ. Org. Chem.
Student Publication: 
No