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Bronsted acid mediated cyclization of enaminones. Rapid and efficient access to the tetracyclic framework of the Strychnos alkaloids.

ABSTRACT: The development of an efficient diastereoselective method that permits rapid construction of the tetracyclic core 17 of the Strychnos-Aspidosperma alkaloids is described. Enaminone 16, synthesized in high yield, has been cyclized under the influence of a Brønsted acid to provide the core tetracyclic framework 17 of the Strychnos alkaloids in optically active form or alternatively to the ?-ketoester tetrahydro-?-carboline (THBC) unit 18, by varying the equivalents of acid and the molar concentration. Attempts to utilize 18 to form the C?-C?? bond of the akuammiline related alkaloids represented by strictamine (22), using metal-carbenoid chemistry, are also described.

SUBMITTER: Edwankar RV

PROVIDER: S-EPMC3288251 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature

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Brønsted acid mediated cyclization of enaminones. Rapid and efficient access to the tetracyclic framework of the Strychnos alkaloids.

Edwankar Rahul V RV Edwankar Chitra R CR Namjoshi Ojas A OA Deschamps Jeffrey R JR Cook James M JM

Journal of natural products 20120118 2

The development of an efficient diastereoselective method that permits rapid construction of the tetracyclic core 17 of the Strychnos-Aspidosperma alkaloids is described. Enaminone 16, synthesized in high yield, has been cyclized under the influence of a Brønsted acid to provide the core tetracyclic framework 17 of the Strychnos alkaloids in optically active form or alternatively to the β-ketoester tetrahydro-β-carboline (THBC) unit 18, by varying the equivalents of acid and the molar concentrat ...[more]

PMID: 22257244

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