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Total synthesis
About: Total synthesis is a research topic. Over the lifetime, 25578 publications have been published within this topic receiving 489319 citations.
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TL;DR: The first total syntheses of higher-order members of the polypyrrolidinoindoline alkaloid family are reported and rigorously confirms its relative and absolute configuration.
Abstract: The first total syntheses of higher-order members of the polypyrrolidinoindoline alkaloid family are reported. The synthesis of quadrigemine C (1) and psycholeine (3) begins with synthetic meso-chimonanthine (4), which is synthesized from commercially available oxindole and isatin in 13 steps and 35% overall yield. Double Stille cross coupling of diiodide 7, available in three steps from 4, with vinylstannane 8 produces dibutenanilide 9. Double catalytic asymmetric Heck cyclization of 9 simultaneously installs the two peripheral quaternary stereocenters and desymmetrizes this advanced meso precursor to deliver the chiral, decacyclic intermediate 11 in 62% yield and 90% ee. In two additional steps, 11 is converted to 1, which upon treatment with acid generates 3. The synthesis of quadrigemine C (1), which rigorously confirms its relative and absolute configuration, was executed in 19 linear steps (2% overall yield) from commercially available starting materials.
133 citations
TL;DR: A number of representative total syntheses are highlighted that demonstrate the impact of the Mukaiyama aldol reaction and the underlying mechanistic rationale that determines the stereochemical outcomes are discussed.
Abstract: Four decades since Mukaiyama's first reports on the successful application of silicon and boron enolates in directed aldol reactions, the ability of this highly controlled carbon-carbon bond-forming method to simultaneously define stereochemistry, introduce complexity, and construct the carbon skeleton with a characteristic 1,3-oxygenation pattern has made it a powerful tool for natural product synthesis. This Minireview highlights a number of representative total syntheses that demonstrate the impact of the Mukaiyama aldol reaction and discusses the underlying mechanistic rationale that determines the stereochemical outcomes.
133 citations
TL;DR: An asymmetric synthesis of the quinone epoxide dimer (+)-torreyanic acid has been accomplished employing [4 + 2] dimerization of diastereomeric 2H-pyran monomers which establishes the biosynthetic relationship between these two natural products.
Abstract: An asymmetric synthesis of the quinone epoxide dimer (+)-torreyanic acid (48) has been accomplished employing [4 + 2] dimerization of diastereomeric 2H-pyran monomers. Synthesis of the related monomeric natural product (+)-ambuic acid (2) has also been achieved which establishes the biosynthetic relationship between these two natural products. A tartrate-mediated nucleophilic epoxidation involving hydroxyl group direction facilitated the asymmetric synthesis of a key chiral quinone monoepoxide intermediate. Thermolysis experiments have also been conducted on a model dimer based on the torreyanic acid core structure and facile retro Diels-Alder reaction processes and equilibration of diastereomeric 2H-pyrans have been observed. Theoretical calculations of Diels-Alder transition states have been performed to evaluate alternative transition states for Diels-Alder dimerization of 2H-pyran quinone epoxide monomers and provide insight into the stereocontrol elements for these reactions.
133 citations
TL;DR: In this paper, the synthesis of (+)- and (-)-epibatidine (exo-2-(2-chloropyridin-5-yl)-7-azabicyclo[2.2.1]heptane) via reaction of 5-lithio-2-loropyridine with (+)-and (-)-N-BOC-7-AZA-1-one is described.
Abstract: The synthesis of (+)- and (-)-epibatidine (exo-2-(2-chloropyridin-5-yl)-7-azabicyclo[2.2.1]heptane) via reaction of 5-lithio-2-chloropyridine with (+)- and (-)-N-BOC-7-azabicyclo [2.2.1]heptan-2-one is described. The absolute configuration of the natural product is shown to be 1R,2R,4S
132 citations
TL;DR: New classes of nucleophiles, pyrroles, and N-methoxyamides were developed for Pd-catalyzed AAA reactions, and the feasibility of accessing (-)-agelastatin A from the same enantiomer of the chiral catalyst from the other regioisomeric piperazinone is indicated.
Abstract: New classes of nucleophiles, pyrroles, and N-methoxyamides were developed for Pd-catalyzed AAA reactions By varying the functional groups at the 2-position of pyrroles, either regioisomer of the piperazinone is available Using one regioisomer, the total synthesis of (+)-agelastatin A in 10 total steps is accomplished For this synthesis, a new copper-catalyzed aziridination and an indium-catalyzed oxidative ring opening of a N-tosylaziridine were developed The feasibility of accessing (−)-agelastatin A from the same enantiomer of the chiral catalyst from the other regioisomeric piperazinone is indicated
132 citations