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Start Over Author "Sarpong, Richmond" Journal angewandte chemie
19 results on '"Sarpong, Richmond"'

1. Total Synthesis of (±)‐Baphicacanthcusine A Enabled by Sequential Ring Contractions.

Author

Sinclair, Paul P. and Sarpong, Richmond

Subjects
*CHEMICAL synthesis, *NATURAL products, *RING formation (Chemistry), *INDOLE compounds, *OXYGEN in the blood
Abstract

Reported herein is the first total synthesis of the poly‐pseudoindoxyl natural product baphicacanthcusine A. The synthesis leverages the oxidative rearrangement of indoles to pseudoindoxyls to install vicinal pseudoindoxyl heterocycles in a diastereoselective manner. Key steps include an acid‐mediated cyclization/indole transposition, two diastereoselective oxidative ring contractions, and a site‐selective C−H oxygenation. The synthesis of the oxidation precursors was guided by recognition of an element of hidden symmetry. This work provides a foundation for the chemical synthesis of other poly‐pseudoindoxyl alkaloids. [ABSTRACT FROM AUTHOR]

Published
2024
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2. Unified Synthesis of 2‐Isocyanoallopupukeanane and 9‐Isocyanopupukeanane through a "Contra‐biosynthetic" Rearrangement.

Author

Hardy, Melissa A., Hayward Cooke, Jack, Feng, Zhitao, Noda, Kenta, Kerschgens, Isabel, Massey, Lynée A., Tantillo, Dean J., and Sarpong, Richmond

Subjects
NATURAL products, RING formation (Chemistry)
Abstract

Herein, we describe our synthetic efforts toward the pupukeanane natural products, in which we have completed the first enantiospecific route to 2‐isocyanoallopupukeanane in 10 steps (formal synthesis), enabled by a key Pd‐mediated cyclization cascade. This subsequently facilitated an unprecedented bio‐inspired "contra‐biosynthetic" rearrangement, providing divergent access to 9‐isocyanopupukeanane in 15 steps (formal synthesis). Computational studies provide insight into the nature of this rearrangement. [ABSTRACT FROM AUTHOR]

Published
2024
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19. Intramolecular C(sp3)N Coupling by Oxidation of Benzylic C,N-Dianions.

Author

Jeffrey, Jenna L., Bartlett, Emily S., and Sarpong, Richmond

Abstract

Clever verknüpft! Eine intramolekulare C(sp3) ‐ N ‐ Kupplung zur Bildung von Azacyclen wird beschrieben. Die Reaktion verläuft über die Oxidation von benzylischen C,N ‐ Dianionen mit Iod und knüpft an eine frühere Entdeckung bei der Synthese von Lyconadin A an. Die vorliegende Studie nutzt konformativ freie Substrate mit weniger aciden C ‐ H ‐ Bindungen und weniger reaktiven Stickstoffnukleophilen. ZnCl2 wurde als ein wichtiges Additiv identifiziert. [ABSTRACT FROM AUTHOR]

Published
2013
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