2,2-Dimethoxy-5,5-dimethyl-Δ<sup>3</sup>-1,3,4-oxadiazoline

Aasmul, Mona; Heimgartner, Heinz; Mlostoń, Grzegorz

doi:10.1002/047084289x.rn00150

Cited by 3 publications

(2 citation statements)

References 49 publications

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“…Compared with other diazo surrogates, 1,3,4-oxadiazolines exhibit high stability and the unique ability to provide distinct reactive intermediates depending on the conditions used (Scheme A). The well-known reactivity is based on thermolysis to ylides that spontaneously decompose into heteroatom-substituted carbenes. , Along this line, they have been widely studied by Warkentin and implemented as dimethoxycarbene surrogates in the synthesis of structurally diverse heterocycles. − Although effective in the formation of α-X (X = O, N, S) divalent carbon species, 1,3,4-oxadiazolines were only evidenced to give alkylidene carbenes trapped as pyridinium ylides under laser flash photolysis (LFP) at 308 nm. − When exposed to UV light, nonstabilized diazo compounds are, however, generated. − While the first photolysis report dates back to 1968, it was only recently that the Ley group proposed their application as diazo precursors in UV-light-induced aryl–alkyl cross-coupling and C–H functionalization reactions of aldehydes. − …”

Section: Introductionmentioning

confidence: 99%

UV Light Is No Longer Required for the Photoactivation of 1,3,4-Oxadiazolines

et al. 2023

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Carbenes play a key role in a plethora of organic transformations. Although stabilized diazo carbonyl compounds predominate as a source of electrophilic carbenes, the hazardous nature of nonstabilized analogues calls for their in situ generation from stable precursors. Among these, 1,3,4-oxadiazolines serve as diazoalkane surrogates under UV light irradiation. In view of their high stability, diverse reactivities, and straightforward synthesis, milder methodologies for the activation of these compounds that permit the use of UV-light-sensitive substrates are highly valued. Herein, we report the visible-light-induced activation of oxadiazolines by triplet energy transfer catalysis that, in contrast to UVinduced processes, alters their reactivity and enables the generation of carbenes. The formed reactive species react with electron-poor olefins, thereby giving valuable spirocyclopropanes. Mechanistic investigations, both theoretical and experimental, uncover plausible pathways and highlight the importance of the triplet energy transfer steps.

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Section: Introductionmentioning

confidence: 99%

UV Light Is No Longer Required for the Photoactivation of 1,3,4-Oxadiazolines

et al. 2023

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“…24,25 Along this line, they have been widely studied by Warkentin and implemented as dimethoxycarbene surrogates in the synthesis of structurally diverse heterocycles. [26][27][28][29][30] Although effective in the formation of α-X (X = O, N, S) divalent carbon species, 1,3,4-oxadiazolines were only evidenced to give alkylidene carbenes trapped as pyridinium ylides under laser flash photolysis (LFP) at 308 nm. [31][32][33] When exposed to UV light, non-stabilized diazo compounds are however generated.…”

Section: Introductionmentioning

confidence: 99%

UV Light is no Longer Required for the Activation of 1,3,4-Oxadiazolines

Orłowska

Santiago

Krajewski

et al. 2022

Preprint

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Carbenes play a key role in a plethora of organic transformations. Although stabilized diazo carbonyl compounds predominate as a source of electrophilic carbenes, the hazardous nature of non-stabilized analogues calls for their in situ generation from stable precursors. Among these, 1,3,4-oxadiazolines serve as diazoalkane surrogates under UV light irradiation. In view of their diverse reactivities and straightforward synthesis, milder methodologies for the activation of these compounds, that permit the use of UV light-sensitive substrates, are of high significance. Herein, we report the visible-light-induced activation of oxadiazolines by triplet energy transfer catalysis that, in contrast to UV-induced processes, enables generation of carbenes. The formed reactive species react with electron-poor olefins, giving valuable spirocyclopropanes. Mechanistic investigations, both theoretical and experimental, uncover plausible pathways and highlight the importance of the triplet energy-transfer steps.

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