A stereocontrolled total synthesis of (.+-.)-hirsutic acid C

Trost, Barry M.; Shuey, Charles D.; DiNinno, Frank

doi:10.1021/ja00499a043

Cited by 117 publications

(32 citation statements)

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“…9 With the required α,β-unsaturated ester (8) in our hand, the model version of intramolecular Stetter reaction 10 was attempted with the thiazolium catalyst in anhydrous toluene as a solvent as reported by Trost and co-workers for their synthesis of hirsutic acid. 11 To our delight, the reaction proceeded smoothly and furnished compound 9 with overall good diastereoselectivity (12:1) in favour of the conformationally more favourable diastereomer (desired one for our synthetic exercise). The minor diastereomer was also separated and well characterized by standard analytic method (see the ESI for more detail).…”

Section: Resultsmentioning

confidence: 86%

Asymmetric synthesis of dihydroartemisinic acid through intramolecular Stetter reaction

2016

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Section: Resultsmentioning

confidence: 86%

Asymmetric synthesis of dihydroartemisinic acid through intramolecular Stetter reaction

2016

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“…Because aldehydes RCHO can also react with intermediates 81 and give products of benzoin homo-coupling, 81 must be more reactive toward 98 than RCHO for successful intermolecular Stetter reactions. Thus, intramolecular Stetter reactions have found a faster development than intermolecular Stetter reactions [345][346][347], including asymmetric versions [348][349][350]. Nevertheless, using acylsilanes 87 (Scheme 16) and enones of type 98 in the presence of DBU (base), THF (solvent) and thiazolium salt 100 (catalyst), good yields are obtained for the intermolecular Stetter reaction [351].…”

Section: The Stetter Reaction: Umpolung Of Aldehydementioning

confidence: 99%

Organocatalysis: Fundamentals and Comparisons to Metal and Enzyme Catalysis

et al. 2016

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Catalysis fulfills the promise that high-yielding chemical transformations will require little energy and produce no toxic waste. This message is carried by the study of the evolution of molecular catalysis of some of the most important reactions in organic chemistry. After reviewing the conceptual underpinnings of catalysis, we discuss the applications of different catalysts according to the mechanism of the reactions that they catalyze, including acyl group transfers, nucleophilic additions and substitutions, and C-C bond forming reactions that employ umpolung by nucleophilic additions to C=O and C=C double bonds. We highlight the utility of a broad range of organocatalysts other than compounds based on proline, the cinchona alkaloids and binaphthyls, which have been abundantly reviewed elsewhere. The focus is on organocatalysts, although a few examples employing metal complexes and enzymes are also included due to their significance. Classical Brønsted acids have evolved into electrophilic hands, the fingers of which are hydrogen donors (like enzymes) or other electrophilic moieties. Classical Lewis base catalysts have evolved into tridimensional, chiral nucleophiles that are N-(e.g., tertiary amines), P-(e.g., tertiary phosphines) and C-nucleophiles (e.g., N-heterocyclic carbenes). Many efficient organocatalysts bear electrophilic and nucleophilic moieties that interact simultaneously or not with both the electrophilic and nucleophilic reactants. A detailed understanding of the reaction mechanisms permits the design of better catalysts. Their construction represents a molecular science in itself, suggesting that sooner or later chemists will not only imitate Nature but be able to catalyze a much wider range of reactions with high chemo-, regio-, stereo-and enantioselectivity. Man-made organocatalysts are much smaller, cheaper and more stable than enzymes.

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“…Trost and co-workers relied on the Michael and the Stetter reaction to set the relative stereochemistry for the core of hirsutic acid C (Scheme 22) [95]. The Stetter reaction was accomplished in 67% yield with 2.3 eq of 3,4-dimethyl-5-(2’-hydroxyethyl) thiazolium iodide 54 and 50 eq of triethylamine.…”

Section: Stetter Reactionmentioning

confidence: 99%