Asymmetric synthesis of either enantiomer of opium alkaloids and morphinans. Total synthesis of (-)- and (+)-dihydrocodeinone and (-)- and (+)-morphine

Hong, Chang Yee; Kado, Noriyuki; Overman, Larry E.

doi:10.1021/ja00076a086

Cited by 194 publications

(73 citation statements)

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“…[36] This transformation has emerged as one of the most useful tools for organic synthesis [37] and was employed in the groundbreaking total syntheses of taxol by Danishefsky et al [38] and morphine by Overman and co-workers, [39] to name just two of the vast number of examples. [40] An important extension has been the development of asymmetric variants for both intra-as well as intermolecular couplings, which have again found numerous applications in natural product synthesis.…”

Section: Asymmetric Arylation By Heck Reactionsmentioning

confidence: 99%

Catalyzed Asymmetric Arylation Reactions

Bolm

Hildebrand

Muñiz

et al. 2001

Angew. Chem. Int. Ed.

339

124

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Section: Asymmetric Arylation By Heck Reactionsmentioning

confidence: 99%

Catalyzed Asymmetric Arylation Reactions

Bolm

Hildebrand

Muñiz

et al. 2001

Angew. Chem. Int. Ed.

339

124

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“…[105] Stereospecific conversion of the hydroxyl group into dimethylphenylsilyl and the terminal vinyl moiety into an amino substituent (N-DBS) set the stage for an intramolecular iminium ion ± allylsilane cyclization to give the bicyclic system shown in Scheme 43. The bridgehead ring system was established by an intramolecular Heck reaction.…”

Section: Synthesis Of Natural Productsmentioning

confidence: 99%

Reduction of Carbonyl Compounds with Chiral Oxazaborolidine Catalysts: A New Paradigm for Enantioselective Catalysis and a Powerful New Synthetic Method

Corey

Helal

1998

Angewandte Chemie International Edition

1,252

184

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“…This study demonstrated, for the first time, that there is a substantial preference for insertion geometries having the metal-carbon a-bond and the alkene n-bond coplanar. Another 6-ex0 closure from our enantioselective total syntheses of (-)-morphine (40) and its enantiomer was published in 1993 (Scheme 6-7) [12]. The pivotal cyclization of 38 to 39 was accomplished in 60% yield.…”

Section: Six-membered Ringsmentioning

confidence: 98%

Intramolecular Heck Reactions in Natural Product Chemistry

Link¹,

Overman²

1998

Metal‐Catalyzed Cross‐Coupling Reactions

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Over the past decade, the Heck reaction has emerged as a particularly potent reaction for forming carbon-carbon bonds. The reaction cross-couples vinyl or aryl halides, triflates, or similar intermediates with alkenes, utilizing palladium catalysts. Bimolecular Heck reactions generally proceed efficiently only with mono-and disubstituted alkenes. However, the intramolecular variant overcomes this limitation allowing trisubstituted, and even some tetrasubstituted, alkenes to participate effectively. Quarternary carbon centers, which typically are difficult to construct, can be effectively fashioned by intramolecular Heck insertions. Although there are scattered examples of forming small, medium, and large rings by thls reaction, five-, six-, and seven-membered rings are formed most efficiently. Hallmarks of intramolecular Heck reactions are excellent functional group tolerance and predictible regio-and stereochemistry. A telling indication of the utility of intramolecular Heck reactions in preparative organic chemistry is their recent use as the key step in the synthesis of many complex natural products. The Heck reaction has been thoroughly reviewed. However, this review will attempt to fill a more specialized niche: namely, the utility of the intramolecular Heck reaction in natural product synthesis [ 11. Mechanistic OutlineTwo mechanistic variants, termed the "neutral" and "cationic pathways", are presumed to govern Heck reactions. A mechanism for a Heck substitution reaction proceeding via the "neutral pathway" is depicted in Scheme 6-1 [2]. The active catalyst is a coodinatively unsaturated 1Celectron palladium complex 3, which most commonly has two phosphine ligands. In the case of tetrakis(triphenylphosphine)palladium(O), the active catalyst is generated in situ by the loss of two phosphine ligands, 1 + 2 + 3 (L= triphenylphosphine). Oxidative addition of a vinyl or aryl halide then provides palladium(I1) intermediate 4. Loss of a ligand, coordination of an alkene, syn insertion, and recoordination of ligand then yields u-alkylpalladium complex 5. Internal rotation to provide 6 and syn B-hydride elimination provide alkene 7 and the hydridopalladium complex 8. A stoichiometric amount of base then regenerates the active catalyst 3.When the substrate is a triflate, or the reaction of halide substrates is carried out in the presence of halide scavengers, a variant of this mechanism in which the palladium(I1) intermediates are cationic is followed [lg, 31. The "cationic pathway" is illustrated in Scheme 6-2. Oxidative addition yields the palladium(I1) intermediate 9 and loss of the 23 1Metal-catalyzed Cross-coupling Reactions Edited by François Diederich, Peter J. Stang

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Asymmetric synthesis of either enantiomer of opium alkaloids and morphinans. Total synthesis of (-)- and (+)-dihydrocodeinone and (-)- and (+)-morphine

Cited by 194 publications

References 0 publications

Catalyzed Asymmetric Arylation Reactions

Catalyzed Asymmetric Arylation Reactions

Reduction of Carbonyl Compounds with Chiral Oxazaborolidine Catalysts: A New Paradigm for Enantioselective Catalysis and a Powerful New Synthetic Method

Intramolecular Heck Reactions in Natural Product Chemistry

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