Total synthesis of aspidospermine

Ban, Yoshio; Sato, Yoshihiro; Inoue, Ichizo; Nagai, Masako; Oishi, Takeshi; Terashima, Masanao; Yonemitsu, Osamu; Kanaoka, Yuichi

doi:10.1016/s0040-4039(00)70368-6

Cited by 52 publications

(10 citation statements)

References 7 publications

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“…This is particularly true for the synthesis of indole alkaloids, a group of compounds that have very different structures but that, due to their common biogenetic origin, possess some common structural features . It is not surprising, therefore, that the construction of azapolycyclic ring systems continues to be of wide interest to researchers involved in developing new methods and reagents for organic synthesis. − Indeed, over the past few decades, an impressive number of effective protocols for the synthesis of trialkylindoline alkaloids have been developed, and many of these have also proven to be of value in work directed toward the synthesis of several different classes of alkaloids. − …”

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confidence: 99%

Cycloaddition Reaction of Mesoionic Betaines as an Approach toward Trialkylindoline Alkaloids

1998

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Intramolecular 1,4-dipolar cycloaddition of an anhydro-4-hydroxy-2-oxo-1,3-thiazium hydroxide across a tethered indole pi-bond has been used for the construction of the pentacyclic skeleton of epi-16,17-dihydroeburnamenine. The reaction of 3-ethyl-3-(alkenyl)piperidinones with diketene and trimethylsilyl triflate in benzene at ambient temperature produced annulated pyridones in good yield. The initial reaction involved formation of a N-acetoacetylated amide which was further converted to the pyridone with TMSOTf. The overall process was found to proceed with complete stereospecificity. Treating a sample of 3-ethyl-3-[(E)-4-phenyl-3-butenyl]-2-piperidone with diketene and TMSOTf produced a cycloadduct in 63% yield whose stereochemistry was elucidated by a X-ray crystallographic study. The epimeric Z-isomer produced a different stereoisomer of the annulated dihydropyridone. The mechanism of the annulation involves a TMSOTf induced cyclization followed by proton removal and generation of a cross-conjugated heteroaromatic betaine. This 1,4-dipole undergoes a subsequent intramolecular dipolar cycloaddition across the neighboring pi-bond, and the resulting cycloadduct is subsequently converted to the annulated lactam. A related annulation sequence leading to a key intermediate previously utilized in the synthesis of the (+/-)-vallesamidine has been developed which is based on the intramolecular dipolar cycloaddition of a mesoionic betaine intermediate.

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confidence: 99%

Cycloaddition Reaction of Mesoionic Betaines as an Approach toward Trialkylindoline Alkaloids

1998

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“…Most of the 250-plus compounds in this class share a pentacyclic core, from the clinical anticancer therapeutics vincristine and vinblastine to the simpler aspidospermidine [60]. To address the challenging synthetic features of the aspidosperma alkaloids, many clever synthetic approaches have been reported [61–62]. One popular target in this family is aspidospermine ( 36 , Scheme 8).…”

Section: Resultsmentioning

confidence: 99%

Formal total syntheses of classic natural product target molecules via palladium-catalyzed enantioselective alkylation

Liu¹,

Liniger²,

McFadden³

et al. 2014

Beilstein J. Org. Chem.

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SummaryPd-catalyzed enantioselective alkylation in conjunction with further synthetic elaboration enables the formal total syntheses of a number of “classic” natural product target molecules. This publication highlights recent methods for setting quaternary and tetrasubstituted tertiary carbon stereocenters to address the synthetic hurdles encountered over many decades across multiple compound classes spanning carbohydrate derivatives, terpenes, and alkaloids. These enantioselective methods will impact both academic and industrial settings, where the synthesis of stereogenic quaternary carbons is a continuing challenge.

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“…Heating this compound in benzene with p-toluenesulfonic acid, followed by addition of ethylene glycol and heating to reflux, provided dioxolane 221 as a single diastereomer, in 85% yield, through a conjugate addition reaction. Reduction of the lactam with lithium aluminum hydride and removal of the acetal then provided amino ketone 222, a compound that had previously been converted into the natural product by Stork and Dolfini, 66 Ban et al, 71 Stevens et al, 72 and Shishido and co-workers. 67 Scheme 46…”

Section: Diastereoselective Alkylation Of Chiral Lactamsmentioning

confidence: 99%

Asymmetric Syntheses of Oxindole and Indole Spirocyclic Alkaloid Natural Products

Trost¹,

Brennan²

2009

Synthesis

1,020

206

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This review highlights the advances in the literature up to May 2009 in the synthesis of spirocyclic indoline natural products. The focus is on formation of the spirocyclic chiral center, including both enantioselective and diastereoselective methods. This review is split into two main sections, the first consisting of the formation of spirooxindoles and their application towards oxindole alkaloids, and the second covering asymmetric synthesis of spiroindoline natural products. Conclusion

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Total synthesis of aspidospermine

Cited by 52 publications

References 7 publications

Cycloaddition Reaction of Mesoionic Betaines as an Approach toward Trialkylindoline Alkaloids

Cycloaddition Reaction of Mesoionic Betaines as an Approach toward Trialkylindoline Alkaloids

Formal total syntheses of classic natural product target molecules via palladium-catalyzed enantioselective alkylation

Asymmetric Syntheses of Oxindole and Indole Spirocyclic Alkaloid Natural Products

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