Volume 136, Issue 1 e202315284
Zuschrift

Total Synthesis of (+)-Discorhabdin V**

Brandon C. Derstine

Brandon C. Derstine

Department of Chemistry, Stanford University, Stanford, CA 94305 USA

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Alina J. Cook

Alina J. Cook

Department of Chemistry, Stanford University, Stanford, CA 94305 USA

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James D. Collings

James D. Collings

Department of Chemistry, Stanford University, Stanford, CA 94305 USA

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Dr. Joseph Gair

Dr. Joseph Gair

Merck & Co., Inc., Boston, MA 02115 USA

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Prof. Dr. Josep Saurí

Prof. Dr. Josep Saurí

Institut Químic de Sarrià (IQS), 08017 Barcelona, Catalonia, Spain

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Dr. Eugene E. Kwan

Corresponding Author

Dr. Eugene E. Kwan

Merck & Co., Inc., Boston, MA 02115 USA

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Prof. Dr. Noah Z. Burns

Corresponding Author

Prof. Dr. Noah Z. Burns

Department of Chemistry, Stanford University, Stanford, CA 94305 USA

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First published: 13 November 2023
**

A previous version of this manuscript has been deposited on a preprint server (https://doi.org/10.26434/chemrxiv-2023-tdhwj).

Abstract

The discorhabdin natural products are a large subset of pyrroloiminoquinone alkaloids with a myriad of biological activities. Despite garnering much synthetic attention, few members have thus far been completed, particularly those featuring a bridging carbon-nitrogen bond that is found in numerous discorhabdins, including discorhabdin V. Herein we report the first total synthesis and full stereochemical assignment of (+)-discorhabdin V. To access the pyrroloiminoquinone we developed a convergent N-alkylation/oxidative aminocyclization/bromination cascade that joins two key components, which are both made on multigram scale. An intramolecular Heck reaction then forms the quaternary carbon center in an intermediate containing the carbon-nitrogen bridge, and a reductive N,O-acetal cyclization sequence introduces the final piperidine ring. Furthermore, we have established the relative configuration of (+)-discorhabdin V through experimental NOESY data and DP4 NMR probability calculations. The absolute configuration of the natural product has also been determined by circular dichroism and the use of an amino acid derived chiral starting material. Our work represents one of only two reports of a total synthesis of a nitrogen-bridged discorhabdin and paves the way for future biological evaluation of such compounds.

Data Availability Statement

The data that support the findings of this study are available in the supplementary material of this article.

The full text of this article hosted at iucr.org is unavailable due to technical difficulties.