Diastereoselective Tandem Addition−Cyclization Reactions of Unsaturated Tertiary Amines Initiated by Photochemical Electron Transfer (PET)

Bertrand, Samuel; Hoffmann, Norbert; Humbel, Stéphane; Pete, Jean‐Pierre

doi:10.1021/jo001166l

Cited by 92 publications

(66 citation statements)

References 52 publications

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“…[18,19,30,34,35] In general, the simple a functionalisation of such compounds, for example in the case of the BaylisHillman [34,36] reaction, is more complex. Recently, a similar Lewis acid catalysed reaction was published.…”

Section: Introductionmentioning

confidence: 99%

Stereoselective Triplet‐Sensitised Radical Reactions of Furanone Derivatives

Jahjah

Gassama

Bulach

et al. 2010

Chemistry A European J

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The stereo- and regioselectivity of triplet-sensitised radical reactions of furanone derivatives have been investigated. Furanones 7a,b were excited to the (3)pipi* state by triplet energy transfer from acetone. Intramolecular hydrogen abstraction then occurred such that hydrogen was transferred from the tetrahydropyran to the beta position of the furanone moiety. Radical combination of the tetrahydropyranyl and the oxoallyl radicals led to the final products 8a,b. In the intramolecular reaction, overall, a pyranyl group adds to the alpha position of the furanone. The effect of conformation was first investigated with compounds 9a,b carrying an additional substituent on the tether between the furanone and pyranyl moiety. Further information on the effect of conformation and the relative configuration at the pyranyl anomeric centre and the furanone moiety was obtained from the transformations of the glucose derivatives 12, 14, 17 and 18. Radical abstraction occurred at the anomeric centre and at the 5'-position of the glucosyl moiety. Computational studies of the hydrogen-abstraction step were carried out with model structures. The activation barriers of this step for different stereoisomers and the abstraction at the anomeric centre and at the 6'-position of the tetrahydropyranyl moiety were calculated. The results of this investigation are in accordance with experimental observations. Furthermore, they reveal that the reactivity and regioselectivity are mainly determined in the hydrogen-abstraction step. Intramolecular hydrogen abstraction (almost simultaneous electron and proton transfer) in (3)pipi* excited furanones only takes place under restricted structural conditions in a limited number of conformations that are defined by the relative configuration of the substrates. It is observed that in the biradical intermediate, back-hydrogen transfer occurs leading to the starting compound. In the case of glucose derivatives, this reaction led to epimerisation at the anomeric centre.

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Section: Introductionmentioning

confidence: 99%

Stereoselective Triplet‐Sensitised Radical Reactions of Furanone Derivatives

Jahjah

Gassama

Bulach

et al. 2010

Chemistry A European J

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“…(2,6-Dimethyl-4H-pyran-4-ylidene)-malononitrile was synthesized by refluxing 2,6-dimethyl-γ-pyrone and malononitrile in the presence of acetic anhydride for 45 min followed by removal of the resultant acetic acid under vacuum and recrystallization from cyclohexane 42 . Dimethylaniline-d6 was synthesized from freshly distilled aniline and d3-iodomethane in the presence of sodium carbonate 43 .…”

Section: Synthesis Of Dcm-d6mentioning

confidence: 99%

Excited State Structural Dynamics of Carotenoids and ChargeTransfer Systems

Tassle¹,

Justin²

2006

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“…然而, 当令其与苯甲醚进行反应时, 没有任何反应发生(表 2, Entry 9). 之后, 我们又研究了芳香醛底物芳环上的电子效应对其反应性的影响, 发现当芳环上连有弱给电子基团或氢原子时, 目标反应同样能够顺利进行(表 2, Entries 10,11). 然而, 当芳环上连有强拉电子基团时, 此反应不能顺利生产目标产物(表 2, Entries 12, 13).…”

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