Confirmation of the Revised Structure of Samoquasine A and a Proposed Structural Revision of Cherimoline

Francis Dhoro, Jesse Parkin-Gibbs, Matthew McIldowie, Brian W. Skelton, Matthew J. Piggott

Research output: Contribution to journalArticle

Abstract

The identity of the natural product samoquasine A has remained obscure since its isolation from custard apple seeds in 2000. One of the proposed structures, benzo[f]phthalazin-4(3H)-one, was prepared in two steps by regioselective ortho-lithiation/formylation of N,N-diisopropyl-2-naphthylamide, followed by cyclization with hydrazine, but was shown to be different from the natural product. Perlolidine, another candidate structure, was synthesized by a novel route involving a β-selective Heck reaction of butyl vinyl ether. Both perlolidine and samoquasine A are converted by trimethylsilyldiazomethane into the same N-methyl derivative. In addition, the 13C NMR spectra of perlolidine and another structurally mis-assigned natural product, cherimoline, are almost identical. Thus, both samoquasine A and cherimoline are actually perlolidine.

Original languageEnglish
Pages (from-to)1658-1665
Number of pages8
JournalJournal of Natural Products
Volume81
Issue number7
DOIs
Publication statusPublished - 27 Jul 2018

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Biological Products
hydrazine
Cyclization
Malus
perlolidine
Seed
Seeds
Nuclear magnetic resonance
Derivatives

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title = "Confirmation of the Revised Structure of Samoquasine A and a Proposed Structural Revision of Cherimoline",
abstract = "The identity of the natural product samoquasine A has remained obscure since its isolation from custard apple seeds in 2000. One of the proposed structures, benzo[f]phthalazin-4(3H)-one, was prepared in two steps by regioselective ortho-lithiation/formylation of N,N-diisopropyl-2-naphthylamide, followed by cyclization with hydrazine, but was shown to be different from the natural product. Perlolidine, another candidate structure, was synthesized by a novel route involving a β-selective Heck reaction of butyl vinyl ether. Both perlolidine and samoquasine A are converted by trimethylsilyldiazomethane into the same N-methyl derivative. In addition, the 13C NMR spectra of perlolidine and another structurally mis-assigned natural product, cherimoline, are almost identical. Thus, both samoquasine A and cherimoline are actually perlolidine.",
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year = "2018",
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Confirmation of the Revised Structure of Samoquasine A and a Proposed Structural Revision of Cherimoline. / Dhoro, Francis; Parkin-Gibbs, Jesse; McIldowie, Matthew; Skelton, Brian W.; Piggott, Matthew J.

In: Journal of Natural Products, Vol. 81, No. 7, 27.07.2018, p. 1658-1665.

Research output: Contribution to journalArticle

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AU - Dhoro, Francis

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AU - Skelton, Brian W.

AU - Piggott, Matthew J.

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AB - The identity of the natural product samoquasine A has remained obscure since its isolation from custard apple seeds in 2000. One of the proposed structures, benzo[f]phthalazin-4(3H)-one, was prepared in two steps by regioselective ortho-lithiation/formylation of N,N-diisopropyl-2-naphthylamide, followed by cyclization with hydrazine, but was shown to be different from the natural product. Perlolidine, another candidate structure, was synthesized by a novel route involving a β-selective Heck reaction of butyl vinyl ether. Both perlolidine and samoquasine A are converted by trimethylsilyldiazomethane into the same N-methyl derivative. In addition, the 13C NMR spectra of perlolidine and another structurally mis-assigned natural product, cherimoline, are almost identical. Thus, both samoquasine A and cherimoline are actually perlolidine.

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