Acetogenins from Annonaceae: recent progress in isolation, synthesis and mechanisms of action

Abstract

The aim of the present review is to summarise the knowledge about newly isolated acetogenins (ACGs) in the last six years. It will also report the total syntheses that have allowed either the confirmation or the revision of some structures, together with the biological activities and mechanism of action of such interesting natural products. In fact, of the 417 isolated compounds reviewed, over 176 have been added during the period from 1998 to 2004.

Stereoselective Synthesis of Highly Substituted Tetrahydrofurans through Diverted Carbene OH Insertion Reaction

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Abstract:Copper or rhodium catalyzed reaction of diazocarbonyl compounds with β-hydroxyketones gives highly substituted tetrahydrofurans with excellent diastereoselectivity, under mild conditions, in a single step process that starts as a carbene O-H insertion reaction but is diverted by an intramolecular aldol reaction.The tetrahydrofuran ring is a commonly found motif in naturally occurring bioactive compounds, and occurs in structural classes such as lignans, [1] acetogenins, [2] ionophores, [3] and macrolides. [4] Examples include (+)-fragransin A2 [5] and amphidinolide F [6] (Figure 1).

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sp3-sp3 Coupling reactions in the synthesis of natural products and biologically active molecules

“…It belongs to the annonaceous acetogenins, a class of polyketide metabolites, that among other structural features have tetrahydropyran rings in common. 16 A key step in the synthesis relies on borane 21, which was generated in situ by chemoselective hydroboration of the terminal double bond in the precursor of 21 in the presence of the alkyne moiety. The alkyl-alkyl cross-coupling between borane 21 and only 1.2 equiv.…”

Recent advances in the stereoselective synthesis of tetrahydrofurans

“…94a,98 For example, 174 is converted to 176 in 68% yield as a single diastereomer upon treatment with KOtBu and (E)-2-nitro-2-butene (eq 52). 98 The major diastereomer is believed to derive from transition state 175, in which A (1,3) -strain is minimized.…”