A study into asymmetric Nicholas cyclisation reactions

Tyrrell, Elizabeth; Millet, Julien; Tesfa, Kibur Hunie; Williams, Neil; Mann, Alastair; Tillett, Caroline; Muller, Christophe

doi:10.1016/j.tet.2007.09.077

Cited by 16 publications

(7 citation statements)

References 37 publications

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“…For the synthesis of enediynes 12 and 13 the Nicholas-type macrocyclization of Co-complex 23b through the isobutenyl group was carried out initially using BF 3 ·OEt 2 . Previously these conditions for the cyclization resulted in the formation of both isopropenyl and fluoroisopropyl groups depending on the structure of starting compounds. ,, In the case of Co-complex 23b the reaction gave both expected Co-complexes 26 , 27 along with the OH-substituted macrocycle 28 (Scheme ).…”

Section: Results and Discussionsupporting

confidence: 87%

“…It is important to keep in mind that the Co-complex 23b is the common starting compound for both target structures 12 and 13, because the formation of both isopropenyl and F-isopropyl moieties has been observed during the Nicholas cyclization depending on the nature of starting materials and acids. − Therefore, with two starting Co-complexes for the Nicholas cyclization in hand we were ready to synthesize target 10-memered enediynes.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Previously these conditions for the cyclization resulted in the formation of both isopropenyl and fluoroisopropyl groups depending on the structure of starting compounds. 95,97,98 In the case of Cocomplex 23b the reaction gave both expected Co-complexes 26, 27 along with the OH-substituted macrocycle 28 (Scheme 6).…”

Section: T H Imentioning

confidence: 98%

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Relative Reactivity of Benzothiophene-Fused Enediynes in the Bergman Cyclization

et al. 2018

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To find promising analogues of naturally occurring enediyne antibiotics with a sufficient reactivity in the Bergman cyclization and moderately stable under isolation and storage, a scale of relative enediynes reactivity was created on the basis of calculated free activation energies for the Bergman cyclization within 12 known and new benozothiophene, benzene, and cinnoline annulated 9- and 10-membered enediynes. To verify the predicted reactivity/stability balance, three new carbocyclic enediynes fused to a benzothiophene core bearing 3,4,5-trimethoxybenzene, fluoroisopropyl, and isopropenyl substituents were synthesized using the Nicholas-type macrocyclization. It was confirmed that annulation of a 3,4,5-trimethoxybenzene moiety to a 10-membered enediyne macrocycle imparts high reactivity to an enediyne while also conferring instability under ambient temperature. Fluoroisopropyl-substituted 10-membered enediyne from the opposite end of the scale was found to be stable while moderately reactive in the Bergman cyclization. Along with the experimentally confirmed moderate reactivity (DSC kinetic studies), (fluoroisopropyl)enediyne showed a significant DNA damaging activity in plasmid cleavage assays comparable with the known anticancer drug Zeocin.

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Section: Results and Discussionsupporting

confidence: 87%

Section: Results and Discussionmentioning

confidence: 99%

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Relative Reactivity of Benzothiophene-Fused Enediynes in the Bergman Cyclization

et al. 2018

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“…Fluorinated compounds can be prepared using BF 3 •OEt 2 or HBF 4 as the source of fluoride. Within the same year, Tyrrell and co-workers described the synthesis of fluorinated benzopyran derivatives (Scheme 54), 107 while Bertrand and co-workers reported the synthesis of functionalized fluorinated cyclohexane and cycloheptane derivatives (Scheme 55). 108 3.1.1.9.3.…”

Section: Synthetic Methods For the Monofluorination Of Organic Compoundsmentioning

confidence: 99%

Monofluorination of Organic Compounds: 10 Years of Innovation

et al. 2015

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“…A recent closely related example of such a process (Scheme 3) is Tyrrell's cyclization of an alkynyl dicobalt-hexacarbonyl derivative of citronellol to form 2-phenylethynyl-1-isopropenyl-4-methylcyclohexane, 3, a near relative of menthene. 12 Likewise, in earlier work, Marshall 13 used this approach to prepare a cyclododecadienynol, as shown in Scheme 4.…”

Section: Introductionmentioning

confidence: 99%