Link: http://www3.interscience.wiley.com/cgi-bin/abstract/114123312/ABSTRACT
From Prof. Robert M. Williams' group at Colorado State University and Prof. Sachiko Tsukamoto's group at Kanazawa University
Both titled compounds are marine natural products, exhibiting cytotoxicity against various human tumor cell lines.
This is a nice synthesis which also establishes biomimetic synthetic relationship between stephacidin A and notoamide B. The total synthesis of stephacidin A started first with the main feature being an intramolecular Diels-Alder reaction of the prenylated indole and in situ generated azadiene to give the desired cycloadduct in good diastereoselectivity and great yield [syn:anti = 2.4 (61%):1.0 (25%)].
The biosynthetic pathway from stephacidin A to notoamide B was then tested by exposing stephacidin A to an oxaziridine. The indole in the stephacidin A was oxidized to 2-oxo-indole, followed by an in situ pinacol-type rearrangement/ring contraction to give the desired spiro-oxindole core of notoamide B (73%). The authors also noted that this was the first example of using oxaziridine to effect such transformation to give spiro-oxindole efficiently. Further studies of scope of such reaction sequence with oxaziridine are ongoing.
From Prof. Robert M. Williams' group at Colorado State University and Prof. Sachiko Tsukamoto's group at Kanazawa University
Both titled compounds are marine natural products, exhibiting cytotoxicity against various human tumor cell lines.
This is a nice synthesis which also establishes biomimetic synthetic relationship between stephacidin A and notoamide B. The total synthesis of stephacidin A started first with the main feature being an intramolecular Diels-Alder reaction of the prenylated indole and in situ generated azadiene to give the desired cycloadduct in good diastereoselectivity and great yield [syn:anti = 2.4 (61%):1.0 (25%)].
The biosynthetic pathway from stephacidin A to notoamide B was then tested by exposing stephacidin A to an oxaziridine. The indole in the stephacidin A was oxidized to 2-oxo-indole, followed by an in situ pinacol-type rearrangement/ring contraction to give the desired spiro-oxindole core of notoamide B (73%). The authors also noted that this was the first example of using oxaziridine to effect such transformation to give spiro-oxindole efficiently. Further studies of scope of such reaction sequence with oxaziridine are ongoing.
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