Versicolamide B Explained

(-)-Versicolamide B and (+)-Versicolamide B are spiroindole alkaloids isolated from the fungus Aspergillus that belong to a class of naturally occurring 2,5-diketopiperazines.^[1] The versicolamides are structurally complex spiro-cyclized versions of prenylated cyclo(L-Trp-L-Pro) derivatives which possess a unique spiro-fusion to a pyrrolidine at the 3-position of the oxindole core together with the bicyclo[2.2.2]diazaoctane ring system. While (-)-versicolamide B was isolated from the marine fungus Aspergillus sp. ^[2] the enantiomer (+)-versicolamide B was isolated from the terrestrial fungi Aspergillus versicolor NRRL.^[3] The total asymmetric syntheses of both enantiomers have been achieved and the implications of their biosynthesis have been investigated.^[4]

Notes and References

1. 2,5-Diketopiperazines: Synthesis, Reactions, Medicinal Chemistry, and Bioactive Natural Products . Borthwick AD . Chemical Reviews . May 2012 . 112 . 7 . 3641–3716 . 10.1021/cr200398y . 22575049.
2. Tsukamoto S, Kawabata T, Kato H, Greshock TJ, Hirota H, Ohta T, Williams RM . Isolation of Antipodal (−)-Versicolamide B and Notoamides L− N from a Marine-Derived Aspergillus sp . Organic Letters . 11 . 6 . 1297–1300 . February 2009 . 19281134. 10.1021/ol900071c . 2829632.
3. Greshock TJ, Grubbs AW, Jiao P, Wicklow DT, Gloer JB, Williams RM . Isolation, Structure Elucidation, and Biomimetic Total Synthesis of Versicolamide B, and the Isolation of Antipodal (−)‐Stephacidin A and (+)‐Notoamide B from Aspergillus versicolor NRRL 35600 . Angewandte Chemie International Edition . 47 . 19 . 3573–3577 . April 2008 . 18389509 . 10.1002/anie.200800106 . 2829633.
4. Miller KA, Tsukamoto S, Williams RM . Asymmetric total syntheses of (+)-and (−)-versicolamide B and biosynthetic implications . Nature Chemistry . 1 . 1 . 63–68 . April 2009 . 20300443 . 10.1038/nchem.110 . 2840645.