Author: Mario Geffe

Enantioselective Synthesis of (−)-Dihydrocodeine and Formal Synthesis of (−)-Thebaine, (−)-Codeine, and (−)-Morphine from a Deprotonated α-Aminonitrile

The α-benzylation of a deprotonated bicyclic α-aminonitrile, followed by Noyori's asymmetric transfer hydrogenation combined with the Grewe cyclization onto a symmetrical A-ring precursor, are the key steps of a short and high-yielding enantioselective synthesis of the morphinan (-)-dihydrocodeine. This compound can be converted to (-)-thebaine in high yield by known transformations, while (-)-codeine and (-)-morphine are available from an advanced intermediate.

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Synthesis of Carbolines via Microwave-Assisted Cadogan Reactions of Aryl-Nitropyridines

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Xylochemie – Naturstoffsynthese aus Holz

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Back Cover: A Regio- and Diastereoselective Anodic Aryl-Aryl Coupling in the Biomimetic Total Synthesis of (−)-Thebaine (Angew. Chem. Int. Ed. 34/2018)

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Synthesis of a Naphtho-pyrido-Annulated Iodonium Salt and Pd-Catalyzed Transformation to 7H-Naphtho[1,8-bc][1,5]naphthyridine

Nitropyridylnaphthalene is the central intermediate for the synthesis of naphthonaphthyridine and benzo-δ-carboline. Whereas the Cadogan reaction gives the carboline, transformation of the nitro group to iodo followed by oxidation and cyclization results in an iodonium salt. A twofold Pd-catalyzed amination leads to the naphthyridine.

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Titelbild: Xylochemie – Naturstoffsynthese aus Holz (Angew. Chem. 47/2015)

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Chromatographically separable rotamers of an unhindered amide

Surprisingly stable formamide rotamers were encountered in the tetrahydroisoquinoline and morphinan series of alkaloids. We investigated the hindered rotation around the amide bond by dynamic high-performance liquid chromatography (DHPLC) and kinetic measurements of the interconversion of the rotamers which can readily be separated by HPLC as well as TLC. The experimental results of the different methods were compared to each other as well as to results obtained by DFT calculations.

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Eine regio- und diastereoselektive anodische Aryl-Aryl-Kupplung in der biomimetischen Totalsynthese von (−)-Thebain

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ChemInform Abstract: Synthesis of a Naphtho-pyrido-Annulated Iodonium Salt and Pd-Catalyzed Transformation to 7H-Naphtho[1,8-bc][1,5]naphthyridine.

Nitropyridylnaphthalene is the central intermediate for the synthesis of naphthonaphthyridine and benzo-δ-carboline. Whereas the Cadogan reaction gives the carboline, transformation of the nitro group to iodo followed by oxidation and cyclization results in an iodonium salt. A twofold Pd-catalyzed amination leads to the naphthyridine.

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Cover Picture: Xylochemistry-Making Natural Products Entirely from Wood (Angew. Chem. Int. Ed. 47/2015)

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Rücktitelbild: Eine regio- und diastereoselektive anodische Aryl-Aryl-Kupplung in der biomimetischen Totalsynthese von (−)-Thebain (Angew. Chem. 34/2018)

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A Regio- and Diastereoselective Anodic Aryl-Aryl Coupling in the Biomimetic Total Synthesis of (-)-Thebaine.

The biosynthesis of thebaine is based on the regioselective, intramolecular, oxidative coupling of (R)-reticuline. For decades, chemists have sought to mimic this coupling by using stoichiometric oxidants. However, all approaches to date have suffered from low yields or the formation of undesired regioisomers. Electrochemistry would represent a sustainable alternative in this respect but all attempts to accomplish an electrochemical synthesis of thebaine have failed so far. Herein, a regio- and diastereoselective anodic coupling of 3',4',5'-trioxygenated laudanosine derivatives is presented, which finally enables electrochemical access to (-)-thebaine.

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Xylochemistry--Making Natural Products Entirely from Wood.

The first total synthesis of the dimeric berberine alkaloid ilicifoline (ilicifoline B) is reported. Its carbon skeleton is constructed from ferulic acid, veratrole, and methanol. The synthesis reported herein employs starting materials solely derived from wood. The natural product is thus constructed entirely from renewable resources. The same strategy is applied to a formal total synthesis of morphinan alkaloids. The use of wood-derived building blocks (xylochemicals) instead of the conventional petrochemicals represents a sustainable alternative to classical synthetic approaches.

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