|Title||Cytochalasins from an Australian Marine Sediment-Derived Phomopsis sp (CMB-M0042F): Acid-Mediated Intramolecular Cycloadditions Enhance Chemical Diversity|
|Publication Type||Journal Article|
|Year of Publication||2017|
|Authors||Shang Z., Raju R., Salim A.A, Khalil Z.G, Capon R.J|
|Journal||Journal of Organic Chemistry|
|Type of Article||Article|
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.
|Short Title||J. Org. Chem.|