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The first total synthesis of acylphloroglucinol-based natural products faberiones A, B, and E is reported, which were isolated from Hypericum faberi. Total syntheses of faberiones A and B are accomplished in six linear steps from commercially accessible 1,3,5-trimethoxybenzene (methyl protected form of phloroglucinol) in overall yields of 31 and 33% respectively, via simple and straightforward approaches that include acylation, o-methoxy deprotection, selective iodination and tandem-Sonogashira cyclization followed by C-geranylation. Faberione E is achieved in two linear steps from acylphloroglucinol with an overall yield of 57% via geranylation followed by benzopyran formation reaction. [ABSTRACT FROM AUTHOR]

Alkyl enol ethers (AEE) are versatile synthetic intermediates with a unique reactivity pattern. This review article summarizes the synthesis of AEE as well as its reactivity and how enol ether undergoes intermolecular reactions for various bond formation, leading to the construction of several useful organic molecules. The synthetic applications of alkyl enol ethers towards intermolecular bond‐forming reactions include metal‐catalyzed reactions, cycloaddition and heterocycle formation as well as rwactions in the field of natural products synthesis. The achievement of these impressive transformations prove the countless synthetic potential of AEE. The main objective of this review is to bring attentiveness among synthetic chemists to show how AEE extensively can be used to react with both electrophiles as well as nucleophiles, thereby behaving as an ambiphilic reactant. We trust that the unique reactivity pattern of alkyl enol ethers and the fundamental mechanistic idea can attract chemists in AEE chemistry. Exclusively, intermolecular reactions of AEE with other functionalized moieties have not been reviewed to the best of our knowledge. [ABSTRACT FROM AUTHOR]

The first total synthesis of enisorine D, a natural product isolated from the marine sponge Iotrochota cf. iota , is described in 64% overall yield. The target molecule, which is an inhibitor of T3SS-dependent Yope secretion of Y. pseudotuberculosis , is achieved in seven linear steps from tyramine via simple and effective transformations that include bromination, acylation, alkylation, azidation, reduction and routine acid–amine coupling. A total of sixteen analogues are prepared by coupling with eight different cinnamic acids, two bromopyrrole carboxylic acids, five phenyl carboxylic acids and picolinic acid. [ABSTRACT FROM AUTHOR]

A macrocyclic furanobutenolide was crafted from readily available furan building-blocks to set-up a transannular Diels–Alder reaction which delivered the carbocyclic core present in a class of cembranoid diterpene natural products. [ABSTRACT FROM AUTHOR]

Total syntheses of two antimicrobial natural products (±)-cis-neocnidilide and (±)-trans-neocnidilide starting from a readily preparable cyclohexa[b]-fused 5-oxabicyclo[2.1.1]hexane derivative are presented. The diastereomeric tetrahydrofuran tricarboxylate epimers obtained from a BF3⋅OEt2 promoted Grob-type fragmentation of the oxa-bicycle derivative were converted into title natural products by employing pyridinium dichromate/acetic anhydride mediated bis-oxidative cleavage reaction. [ABSTRACT FROM AUTHOR]

Abstract: A total synthesis of bioactive tetracyclic natural product paracaseolide A, embodying an architecturally unusual oxa-bowl framework, has been accomplished from commercially available 5-methyl-2-furfural. The key step involving a thermal [4+2]-dimerization of an appropriately crafted 5-methyl-3-alkenylbutenolide is shown to proceed in a stepwise manner. [Copyright &y& Elsevier]

• Total synthesis of (±) aspidostomide B, C and regioisomeric N -methyl aspidostomide is reported. • An unusual Lewis acid-mediated regioselective epoxide opening is described. • Aspidostomide B, C was achieved in six steps with overall yields of 54.7 and 59.0% respectively. A full account of the total synthesis of aspidostomide B, C, their analogues and our synthetic efforts towards the synthesis of aspidostomide D, which led to the synthesis of regioisomeric N -methyl aspidostomide D, its analogues via epoxide opening strategy is presented. The synthesis of regioisomeric N -methyl aspidostomide D involves an efficient, five-step sequence, with 36.3% overall yield, starting from 3,4,5-tribromo-1H-pyrrole-2-carboxylic acid. The key features of this protocol are intramolecular cyclization, dehydration, oxidation, and a Lewis acid-mediated regioselective epoxide ring opening by C-3 position of 2,5-dibromo-1H-indole to furnish the title compounds. [ABSTRACT FROM AUTHOR]

Synthesis of brominated marine natural product amathamide F is described. Various strategies to construct the enamide functionality required for its synthesis have been explored. Finally, we succeeded in constructing the enamide moiety under a palladium-catalyzed condition. Facile transformation of 2,3,4-tribromo-5-methoxybenzaldehyde to the reported structure of amathamide F involved initial one-carbon-elongation of the aldehyde group followed by its conversion to corresponding enol acetate derivative prior to crucial Pd(II)-catalyzed cross-coupling with ( S )-1-methylpyrrolidine-2-carboxamide. However, due to nonconformity of its NMR spectral data to that of the reported natural isolate, we have confirmed its actual structure through a synthesis. [ABSTRACT FROM AUTHOR]