Formal synthesis of (±)-physostigmine

Morales‐Ríos, Martha S.; Bucio, María A.; Joseph‐Nathan, Pedro

doi:10.1016/0040-4020(96)00176-7

Cited by 23 publications

(8 citation statements)

References 25 publications

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“…Recently, we have shown the Grignard reagent addition to 2-hydroxyindolenines as a useful method for introducing an alkyl group at the C3 position of the indole nucleus. 5 In this paper, we describe our preliminary results regarding the synthesis of debromoflustramine B (1), which also resulted in the syntheses of related derivatives debromoflustramine A (2) and debromoflustramide A (3) via the conjugated addition of the Grignard reagent derived from prenyl bromide to 2-hydroxyindolenines. This method represents a new and general approach for the synthesis of 3a-alkylhexahydropyrrolo[2,3-b]indole-type alkaloids according to the strategy outlined in Scheme 1.…”

mentioning

confidence: 99%

General Approach to the Synthesis of Marine Bryozoan Flustra foliacea Alkaloids: Total Syntheses of Debromoflustramines A and B

1999

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confidence: 99%

General Approach to the Synthesis of Marine Bryozoan Flustra foliacea Alkaloids: Total Syntheses of Debromoflustramines A and B

1999

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“…The preparation of undeuterated compounds 1 – 4 , 6 – 9 and 12 – 18 has already been described3b, 3e, 4a, 5a–c (see Table 1).…”

Section: Methodsmentioning

confidence: 99%

“…In particular, 3‐alkylideneindoline derivatives are useful starting materials in a variety of organic syntheses ranging from ring expansions to additions and heterocyclizations 3. Compounds of this kind are of special interest because of their utility in the synthesis of indole alkaloids 4. The characterization of indolenines 1 – 18 by NMR in CDCl 3 solution has shown that all of them exist as the Z ‐isomer.…”

Section: The Indolenines 1–18mentioning

confidence: 99%

Electron ionization mass spectra of indolenines obtained using sector and ion trap mass spectrometers

Morales‐Ríos

Velasco

Pérez-Rojas

et al. 2005

Rapid Comm Mass Spectrometry

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The electron impact (EI)-induced fragmentations of 18 indolenines were studied using both double-focusing and ion trap mass spectrometers. The compounds used in this study were synthesized to provide correlations of characteristic fragment ions with specific structural differences. In 2-hydroxyindolenines the hydroxy group was involved in a major fragmentation process by interacting with the ester side chain to generate an alpha,beta-unsaturated gamma-lactone structure, with concomitant loss of the corresponding alcohol. In contrast, loss of an alkyl radical, derived solely from the 2-alkoxy group, is a major primary decomposition process for 2-alkoxyindolenines. EI-MS analyses using sector and ion trap spectrometers resulted in similar fragmentation patterns.

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“…34 When heating the mixtures to 160 °C in DMSO, even decarboxylation after hydrolysis can be achieved. 35 It can be concluded that the situation regarding ester hydrolysis is a little bit confusing.…”

Section: Ester Hydrolysis and Transesterificationmentioning

confidence: 99%

Cyanide Anions as Nucleophilic Catalysts in Organic Synthesis

Kieslich¹,

Christoffers²

2021

Synthesis

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The nucleophilic addition of a cyanide anion to a carbonyl group is the basis for several cyanide-catalyzed organic reactions, which are summarized in this review. Since cyanide is also a good leaving group, it is an excellent catalyst for transacylation reactions. As an electron-withdrawing group, it also stabilizes a negative charge in its α-position, thus allowing the umpolung of aldehydes to formyl anion equivalents. The two leading examples are the benzoin condensation and the Michael–Stetter reaction furnishing α-hydroxy ketones and 1,4-dicarbonyl compounds, which are both catalyzed by cyanides. The review also covers variants like the silyl-benzoin coupling, the aldimine coupling and the imino-Stetter reaction. Moreover, some cyanide-catalyzed heterocyclic syntheses are reviewed.1 Introduction2 Nucleophilic Additions2.1 Cyanohydrin Formation2.2 Corey–Gilman–Ganem and Related Oxidation Reactions2.3 Conjugate Addition2.4 Intramolecular Carbocyanation3 Transacylation Reactions3.1 Ester Hydrolysis and Transesterification3.2 Formation of Amides3.3 Ketones from Esters3.4 Esters from Ketones4 Transformations Involving an Umpolung4.1 Benzoin Condensation4.2 Aldimine Coupling4.3 Michael–Stetter Reaction4.4 Imino-Stetter Reaction5 Formation of Heterocycles5.1 Oxazolines from Isocyanoacetates5.2 Imidazoles from TosMIC via Oxazolines5.3 Bargellini Reaction6 Conclusion

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Formal synthesis of (±)-physostigmine

Cited by 23 publications

References 25 publications

General Approach to the Synthesis of Marine Bryozoan Flustra foliacea Alkaloids: Total Syntheses of Debromoflustramines A and B

General Approach to the Synthesis of Marine Bryozoan Flustra foliacea Alkaloids: Total Syntheses of Debromoflustramines A and B

Electron ionization mass spectra of indolenines obtained using sector and ion trap mass spectrometers

Cyanide Anions as Nucleophilic Catalysts in Organic Synthesis

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