Enantioselective Palladium-Catalyzed Decarboxylative Allylation of Carbazolones: Total Synthesis of (−)-Aspidospermidine and (+)-Kopsihainanine A

Catalytic asymmetric assembly of octahydroindolones: divergent synthesis of lycorine-type amaryllidaceae alkaloids (+)-α-lycorane and (+)-lycorine

We report the first catalytic asymmetric approach to octahydroindolones and a divergent enantioselective synthesis of perhydroindole alkaloids, as exemplified by lycorine-type Amaryllidaceae alkaloids (+)-α-lycorane and (+)-lycorine, from a common intermediate by using a highly concise route. The assembly of octahydroindolones employs a catalytic enantioselective 1,4-conjugate addition of nitro dienynes, followed by a TsOH-catalyzed cascade synthesis of highly functionalized enones, and a diastereoselective intramolecular Michael addition.

Enantioselective Pd-Catalysed Deallylative γ-Lactonisation of Propargyl Carbazolone Allyl Carbonates: Mechanistic Insight into their Decarboxylative Allylation

Subjection of N-methyl carbazolone allyl carbonates bearing a propargyl side chain to Pd0 catalysis leads to the formation of enantioenriched γ-lactones, rather than the expected products of decarboxylative allylation. This side reaction has not been observed with the enantioselective decarboxylative allylation of related β-ketoesters, and provides evidence for a mechanism involving turnover limiting decarboxylation from the palladium carboxylate resting state. Following lactonisation, the Pd0 catalyst is regenerated by PdII reductive alkyne coupling.

Catalytic asymmetric synthesis of 1,3-enyne scaffolds: design and synthesis of conjugated nitro dienynes as novel Michael acceptors and development of a new synthetic methodology

A catalytic enantioselective synthesis of 1,3-enynes for the development of nitro dienynes as novel Michael acceptors has been developed.

The Construction of All-Carbon Quaternary Stereocenters by Use of Pd-Catalyzed Asymmetric Allylic Alkylation Reactions in Total Synthesis

All-carbon quaternary stereocenters have posed significant challenges in the synthesis of complex natural products. These important structural motifs have inspired the development of broadly applicable palladium-catalyzed asymmetric allylic alkylation reactions of unstabilized non-biased enolates for the synthesis of enantioenriched α-quaternary products. This microreview outlines key considerations in the application of palladium-catalyzed asymmetric allylic alkylation reactions and presents recent total syntheses of complex natural products that have employed these powerful transformations for the direct, catalytic, enantioselective construction of all-carbon quaternary stereocenters.

Studies on the Enantioselective Synthesis of Carbazolones as Intermediates in Aspidosperma and Kopsia Alkaloid Synthesis

Two strategies for the assembly of homochiral carbazolones have been investigated. The first exploited desymmetrisation of 1,3-cyclohexadione derivatives however this failed to deliver satisfactory outcomes. An orthogonal route exploiting palladium catalysed decarboxylative allylation of racemic carbazolone β-ketoesters has been developed. Herein we report full details on the development of this reaction and clarify apparent discrepancies between our preliminary reports and those of Shao.