Catalytic tin radical mediated tricyclisations. Part 1. Monocyclisation studies †

Kelly, David R.; Picton, Mark R.

doi:10.1039/b000661k

Cited by 12 publications

(5 citation statements)

References 65 publications

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“…Substrates for mono-cyclisation 8, 9a were prepared previously by Ferrier rearrangement 16 of tri-O-acetyl--glucal 6, deacetylation, protection of the 6-hydroxy group 7b and functionalisation of the 4-hydroxy group 8 (Scheme 2). 5 This seemingly straightforward sequence was stymied by poor yields in the selective protection of the 6-hydroxy group 7b and more importantly, complex mixtures of products were produced during allylation or propargylation of the 4-hydroxy group 8 (propargyl = prop-2-ynyl). These precedents did not augur well for extension to the tricyclisation substrates 10.…”

Section: Resultsmentioning

confidence: 99%

“…The previous paper in the series should be consulted for the preparation of some starting materials. 5 All reactions were monitored by thin layer chromatography (TLC) using Merck aluminium backed precoated silica gel plates (0.2 mm, 60, F 254 ) with UV light or ethanolic phosphomolybdic acid (3%) and heat for visualisation. Virtually all products were purified by flash column chromatography using Merck silica gel 60 (70-230 mesh).…”

Section: Methodsmentioning

confidence: 99%

“…A previous successful monocyclisation of a chloropropenyl substituent (50% yield), augured well for this proposal, albeit that the cyclisation requires stoichiometric amounts of the tin hydride reagent. 5 Treatment with TBTH yielded a single major product 43 which was isolated by column chromatography (42% yield). The 1 H-NMR spectrum of the product contained the signals for an intact chloropropenyl group (δ 5.37, d, J 1.2 Hz; 5.25, s) and an acetylenic proton was absent.…”

Section: Conformational Analysis Of Alkyne-alkene-alkene Cyclisationsmentioning

confidence: 99%

“…palladium) mediated processes, because of a dearth of processes for elimination of the initiating radical. 4 In the preceding paper 5 we outlined a strategy for constructing polycyclic molecules using catalytic amounts of organotin radicals. This involves the addition of an organotin radical to an array of unsaturated bonds such that a cascade of addition reactions delivers the radical centre to a position at which the moiety which has initiated the process can be eliminated.…”

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Catalytic tin radical mediated tricyclisations. Part 2 †‡

Kelly

Picton

2000

J. Chem. Soc., Perkin Trans. 1

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Conformational Analysis Of Alkyne-alkene-alkene Cyclisationsmentioning

confidence: 99%

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Catalytic tin radical mediated tricyclisations. Part 2 †‡

Kelly

Picton

2000

J. Chem. Soc., Perkin Trans. 1

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“…112 Furthermore, Chapleur also tributyltin hydride addition on triple bonds, add efficiently on 2,3-double bonds. 114 In recent times, Kelly and Picton 115 and Chiara 116 have proficiently used this methodology. The Chiara application is shown for the stereoselective synthesis of 100, the glycosidic moiety of antifungal GM222712.…”

Section: Synthesis Of Branched-chain Sugarsmentioning

confidence: 99%

Radicals and Carbohydrates

Pérez‐Martín

Suárez

2012

Encyclopedia of Radicals in Chemistry, Biology and Materials

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Transformation of Glycals into 2,3‐Unsaturated Glycosyl Derivatives

Ferrier

Zubkov

2003

Organic Reactions

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Various elimination procedures conducted on appropriate pyranoid and furanoid carbohydrate derivatives, especially on O ‐protected glycosyl halides afford cyclic vinyl ethers which Fischer (inappropriately) named glycals. These are used extensively in general organic synthesis and for the preparation of non‐carbohydrate natural products as well as biologically important complex carbohydrates and glycoconjugates. The best known member, tri‐ O ‐acetyl‐D‐glucal, is normally made from tetra‐ O ‐acetyl‐alpha‐D‐glucopyranosyl bromide, is commercially available, and is used very frequently in this chapter to represent the family in examples of the reactions under discussion. Because of the pronounced region‐ and stereoselectivities with which their addition reactions can be conducted, glycal derivatives are of major importance in synthesis. They also, however, take part in rearrangement processes that, likewise, have proved useful for synthesis. The principal one involves nucleophilic substitution of the allylic group with allylic rearrangement and results in products having double bonds in the 2, 3 positions and new substituents at the anomeric centers. By far the simplest and most commonly used way to this conversion involves the removal of the allylic substituent of the glycal and the generation of highly resonance‐stabilized oxocarbenium ion intermediate. This may then react with nucleophiles at the anomeric center to give products as mixtures of diastereomers. Many examples and variations of this theme are described and form the major part of this chapter, but other ways are also considered Almost no formal mechanistic studies have been carried out on the reactions in this chapter. Categorization of mechanism required for the treatment of this topic has been done on the basis of conditions used, product identification and largely, chemical intuition.

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Catalytic tin radical mediated tricyclisations. Part 1. Monocyclisation studies †

Cited by 12 publications

References 65 publications

Catalytic tin radical mediated tricyclisations. Part 2 †‡

Catalytic tin radical mediated tricyclisations. Part 2 †‡

Radicals and Carbohydrates

Transformation of Glycals into 2,3‐Unsaturated Glycosyl Derivatives

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