Short, Gram-Scale Syntheses of β- and γ-Lycorane Using Two Distinct Photochemical Approaches

Yu, Wai L.; Nunns, Thomas; Richardson, Jeffery; Booker‐Milburn, Kevin I.

doi:10.1021/acs.orglett.7b03960

Cited by 23 publications

(11 citation statements)

References 25 publications

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“…The product was purified by flash chromatography on silica gel, eluting with AcOEt, then 1 % Et 3 N in AcOEt, yielding 27 (8 mg, 0.031, 84 % yield) as an oil. Proton NMR data match those of title compound 27 [24–37] …”

Section: Methodsmentioning

confidence: 55%

“…The first asymmetric synthesis of γ‐lycorane was reported by Mori in 1995, [23] and its structure is considered prototypical for this important class of alkaloids. In just the past five years, well over a dozen new syntheses of the lycorine family have appeared [24–37] . Of these, only one uses a benzene ring as the source of the C ring, which contains all of the stereocenters.…”

Section: Introductionmentioning

confidence: 99%

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Hydroamination of Dihapto‐Coordinated Benzene and Diene Complexes of Tungsten: Fundamental Studies and the Synthesis of γ‐Lycorane

Wilson

Nedzbala

Simpson

et al. 2021

Helvetica Chimica Acta

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Reactions are described for complexes of the form WTp(NO)(PMe3)(η2‐arene) and various amines, where the arene is benzene or benzene with an electron‐withdrawing substituent (CF3, SO2Ph, SO2Me). The arene complex is first protonated to form an η2‐arenium species, which then selectively adds the amine. The resulting η2‐5‐amino‐1,3‐cyclohexadiene complexes can then be subjected to the same sequence with a second nucleophile to form 3‐aminocyclohexene complexes, where up to three stereocenters originate from the arene carbons. Alternatively, 1,3‐cyclohexadiene complexes containing an ester group at the 5 position (also prepared from an arene) can be treated with acid followed by an amine to form trisubstituted 3‐aminocyclohexenes. When the amine is primary, ring closure can occur to form a cis‐fused bicyclic γ‐lactam. Highly functionalized cyclohexenes can be liberated from the tungsten through oxidative decomplexation. The potential utility of this methodology is demonstrated in the synthesis of the alkaloid γ‐lycorane. An enantioenriched synthesis of a lactam precursor to γ‐lycorane is also described. This compound is prepared from an enantioenriched version of the tungsten benzene complex. Regio‐ and stereochemical assignments for the reported compounds are supported by detailed 2D‐NMR analysis and 13 molecular structure determinations (SC‐XRD).

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Section: Methodsmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Hydroamination of Dihapto‐Coordinated Benzene and Diene Complexes of Tungsten: Fundamental Studies and the Synthesis of γ‐Lycorane

Wilson

Nedzbala

Simpson

et al. 2021

Helvetica Chimica Acta

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“…Following our recently reported synthesis of lycorane alkaloid 4 , [12] employing a key Heck cyclisation on a photochemically‐derived substrate, we were led to consider whether simple homologation of the carbon tether might lead directly to the homologated alkaloid series. However, initial investigation of the Heck reaction of iodide 10 a in fact yielded deiodinated material 10 b under the majority of conditions (Table 1).…”

Section: Methodsmentioning

confidence: 99%

Rapid Access to Azabicyclo[3.3.1]nonanes by a Tandem Diverted Tsuji–Trost Process

Steeds

Knowles

et al. 2020

Chemistry A European J

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At hree-step synthesis of the 2-azabicyclo[3.3.1]nonaner ing system from simple pyrroles, employing a combined photochemical/palladium-catalysed approach is reported. Substrate scope is broad,a llowing the incorporation of aw ider ange of functionalityr elevant to medicinal chemistry.M echanistic studies demonstrate that the processo ccurs by acid-assisted CÀNb ond cleavage followed by b-hydride eliminationt of orm ar eactive diene, demonstratingt hat efficient control of what mightb e considered off-cycle reactionsc an result in productive tandem catalytic processes. This represents as hort and versatile route to the biologically important morphan scaffold.

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“…In order to increase the throughput, a flow apparatus was employed allowing roughly 8 g of final material to be isolated after 24 hours of runtime (57% isolated yield). The same flow setup used for various other analogues enabled the intermediate structures to be exploit in the synthesis of more complex natural products, such as (+)-3-demethoxyerythratidinone ( 573 ) and the lycorane alkaloids (illustrated by compound 574 ) [ 511 – 512 ].…”

Section: Reviewmentioning

confidence: 99%

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

Gambacorta¹,

Sharley²,

Baxendale³

2021

Beilstein J. Org. Chem.

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Due to their intrinsic physical properties, which includes being able to perform as volatile liquids at room and biological temperatures, fragrance ingredients/intermediates make ideal candidates for continuous-flow manufacturing. This review highlights the potential crossover between a multibillion dollar industry and the flourishing sub-field of flow chemistry evolving within the discipline of organic synthesis. This is illustrated through selected examples of industrially important transformations specific to the fragrances and flavours industry and by highlighting the advantages of conducting these transformations by using a flow approach. This review is designed to be a compendium of techniques and apparatus already published in the chemical and engineering literature which would constitute a known solution or inspiration for commonly encountered procedures in the manufacture of fragrance and flavour chemicals.

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Short, Gram-Scale Syntheses of β- and γ-Lycorane Using Two Distinct Photochemical Approaches

Abstract: The synthesis of two diastereomeric members of the lycorane alkaloid family is reported. Although the routes are quite different in their approach, both involve the use of photochemistry as a key step, enabling the synthesis of gram quantities in the case of β-lycorane.

Cited by 23 publications

References 25 publications

Hydroamination of Dihapto‐Coordinated Benzene and Diene Complexes of Tungsten: Fundamental Studies and the Synthesis of γ‐Lycorane

Hydroamination of Dihapto‐Coordinated Benzene and Diene Complexes of Tungsten: Fundamental Studies and the Synthesis of γ‐Lycorane

Rapid Access to Azabicyclo[3.3.1]nonanes by a Tandem Diverted Tsuji–Trost Process

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

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