A Photochemical Approach to the Gelsemine Skeleton

Avent, Anthony G.; Byrne, Paul; Penkett, Clive S.

doi:10.1021/ol991119j

Cited by 32 publications

(8 citation statements)

References 24 publications

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“…Penkett and co-workers165 assembled the gelsemine skeleton by meta photocycloaddition, where the cyclopropane ring in 333 was cleaved by epoxidation (because the usual bromination gave the wrong regioselectivity) (Scheme 83). Photolysis of 332 led to additional isomers 334 and 335, arising from an initial ortho cycloadduct, undergoing first an electrocyclic ring opening into a cyclooctatriene and then reclosing by another electrocyclic process into a series of isomeric bicyclo[4.2.0]octenes.…”

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confidence: 99%

Arene–Alkene Cycloaddition

2016

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Cycloadditions are among the most efficient chemical processes, combining atom economy, stereospecificity, and the ability to generate molecular complexity in a single step. Aromatic rings would in principle be ideal reaction partners, as they contain, at least from the topological point of view, both olefinic and diene subunits; however, the stability of the conjugated aromatic system would be broken by cycloaddition reactions, which are therefore rarely applied, because kinetics and thermodynamics hinder the process. From that aspect, photochemical activation opens interesting perspectives, as one can selectively provide excess energy to one of the reactants but not to the product, thus preventing thermal back reaction. Indeed, aromatic rings show a rich photochemistry, ranging from isomerizations, substitutions, and additions to cycloadditions. In this review, we will focus on cycloadditions, covering literature from early observations up to the present.

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confidence: 99%

Arene–Alkene Cycloaddition

2016

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“…Rearrangement of the resulting allylic bromide to the more stable regioisomer at this stage occurs readily and debromination can be achieved on treatment with tributyltin hydride. Penkett has shown that 3-chloroperbenzoic acid ( m -CPBA) can take the role of an electrophile in the epoxidation of the double bond [ 56 ] and also demonstrated that the meta photocycloaddition products containing a methoxy group at position 1 can be converted in a Heck-type reaction [ 57 – 58 ]. The intermediate palladium σ-complex, formed by insertion, opens the cyclopropane ring and arylated bicyclo[3.2.1]octane derivatives are obtained.…”

Section: Reviewmentioning

confidence: 99%

The arene–alkene photocycloaddition

Streit¹,

Bochet²

2011

Beilstein J. Org. Chem.

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“…An interesting photochemical approach to the bicyclo[3.2.1] skeleton of gelsemine was reported by Penkett and co‐workers (Scheme ) 22. Photolysis of 3‐(phenoxydimethylsilyl)prop‐1‐ene ( 104 ) afforded the desired photoadduct 105 23 as the major product.…”

Section: Strategies For the Assembly Of The Bicyclo[321]octane Smentioning

confidence: 99%