Di-t-butyl Hyponitrite

Boukouvalas, John; Cren, Sylvaine; Renaud, Philippe

doi:10.1002/047084289x.rd062.pub2

Cited by 14 publications

(17 citation statements)

References 52 publications

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“…Precautions : The preparation and manipulation of DTBHN [42] and DTBPO [88] must be conducted behind a blast shield. DTBHN has been reported to be insensitive to scratching and is considered as handleable [41] .…”

Section: Methodsmentioning

confidence: 99%

“…The use of di‐ tert ‐butyl peroxide was not considered as an option since temperatures ≥120 °C are required for its homolysis [39,40] . Interestingly, the thermal homolytic scission of di‐ tert ‐butyl hyponitrite (DTBHN) [41,42] takes place facilely at moderate temperatures (40–70 °C; t 1/2 =29 min at 65 °C, neat) to result in the simultaneous formation of two tert ‐butoxyl radicals and extrusion of molecular nitrogen (Scheme 2, top). A first order rate in [DTBHN] with constant of k f =3.85–4.00×10 4 s −1 was measured for this decomposition at 65 °C in isooctane [41] .…”

Section: Introductionmentioning

confidence: 99%

“…Even more interesting, this fragmentation is accelerated in polar ( k β =6.4×10 4 s −1 in acetonitrile at 22 °C) and protic solvents ( k β =1.4×10 6 s −1 in water at 22 °C) [43] . Up to now, most radical initiations using DTBHN involve rapid reactions of tert ‐butoxyl radicals with oxophilic species such as organoboron and ditin derivatives as well as hydrogen atom donors such as tin hydrides and silanes (Scheme 2, top, grey) [42] . However, when no such species is present in the reaction mixture, DTBHN is expected to be a source of methyl radicals and therefore a powerful system to initiate halogen/chalcogen transfer processes from a variety of radical precursors.…”

Section: Introductionmentioning

confidence: 99%

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Methyl Radical Initiated Kharasch and Related Reactions

Tappin

Renaud

2020

Adv Synth Catal

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An improved procedure to run halogen atom and related chalcogen group transfer radical additions is reported. The procedure relies on the thermal decomposition of di‐tert‐butylhyponitrite (DTBHN), a safer alternative to the explosive diacetyl peroxide, to produce highly reactive methyl radicals that can initiate the chain process. This mode of initiation generates byproducts that are either gaseous (N2) or volatile (acetone and methyl halide) thereby facilitating greatly product purification by either flash column chromatography or distillation. In addition, remarkably simple and mild reaction conditions (refluxing EtOAc during 30 minutes under normal atmosphere) and a low excess of the radical precursor reagent (2 equivalents) make this protocol particularly attractive for preparative synthetic applications. This initiation procedure has been demonstrated with a broad scope since it works efficiently to add a range of electrophilic radicals generated from iodides, bromides, selenides and xanthates over a range of unactivated terminal alkenes. A diverse set of radical trap substrates exemplifies a broad functional group tolerance. Finally, di‐tert‐butyl peroxyoxalate (DTBPO) is also demonstrated as alternative source of tert‐butoxyl radicals to initiate these reactions under identical conditions which gives gaseous by‐products (CO2).

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Methyl Radical Initiated Kharasch and Related Reactions

Tappin

Renaud

2020

Adv Synth Catal

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“…[42] Up to now, most radical initiations using DTBHN involve rapid reactions of tert-butoxyl radicals with oxophilic species such as organoboron and ditin derivatives as well as hydrogen atom donors such as tin hydrides and silanes (Scheme 2, top, grey). [41] However, when no such species is present in the reaction mixture, DTBHN is expected to be a good source of methyl radicals and therefore a powerful system to initiate halogen atom transfer process from a variety of radical precursors. To the best of our knowledge, the DTBHN-methyl radical mediated initiation has only been used by Trauner and coworkers for a conversion of a xanthate to a bromide (Scheme 2, middle).…”

Section: Introductionmentioning

confidence: 99%

Methyl Radical Initiated Kharasch and Related Reactions

Tappin¹,

Renaud²

2020

Preprint

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An improved procedure to run halogen atom and related chalcogen group transfer radical additions is reported. The procedure relies on the thermal decomposition of di-tert-butylhyponitrite (DTBHN), a safer alternative to the explosive diacetyl peroxide, to produce highly reactive methyl radicals that can initiate the chain process. This mode of initiation generates byproducts that are either gaseous (N2) or volatile (acetone and methyl halide) thereby facilitating greatly product purification by either flash column chromatography or distillation. In addition, remarkably simple and mild reaction conditions (refluxing EtOAc during 30 minutes under normal atmosphere) and a low excess of the radical precursor reagent (2.0 equivalents) make this protocol particularly attractive for preparative synthetic applications. This initiation procedure has been demonstrated with a broad scope since it works efficiently to add a range of electrophilic radicals generated from iodides, bromides, selenides and xanthates over a range of unactivated terminal alkenes. A diverse set of radical trap substrates exemplifies a broad functional group tolerance. Finally, di-tert-butyl peroxyoxalate (DTBPO) is also demonstrated as alternative source of tert-butoxyl radicals to initiate these reactions under identical conditions which gives gaseous byproducts (CO2).

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“…Therefore, we decided to use the triisopropylsilyl (TIPS)protected ethynyl sulfone as radical trap to introducet he ethynyl moiety.G ratifyingly and in contrastt ot he TMS-protected sulfone, the preparation of the triisopropylethynyl phenyl sulfone was achieved in 98 %y ield from TIPS-acetylene and the corresponding product 2b is bench stable. Running the hydroalkynylation reaction with this reagent afforded the TIPS-protected alkyne trans-2b in 43 %y ield when run with di-tertbutyl hyponitrite [80] (DTBHN)a sa ni nitiator.B yi nitiating the reaction with di-tert-butyl peroxyoxalate [81,82] (DTBPO), the reaction time could be decreased from 1day (DTBHN) down to 40 min, which resulted in an increased yield of 70 %( up to 85 %o ns mall scale).A ne nantiomeric purity of 95:5 was determined after desilylation to 3 by HPLC analysis. This enantiomeric purity is identicalw ithin experimental error to the one measured for 2-furanylcyclopentanol obtainedu pon oxidation of the organoborane intermediate with NaOH/H 2 O 2 (see the Supporting Information) demonstrating that the radical process is taking place without epimerization.…”

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confidence: 99%

A Short Synthesis of (+)-Brefeldin C via Enantioselective Radical Hydroalkynylation

Gnägi¹,

Martz²,

Meyer³

et al. 2019

Preprint

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Av ery conciset otal synthesis of (+ +)-brefeldin C starting from 2-furanylcyclopentene is described. This approach is based on an unprecedented enantioselective radical hydroalkynylation process to introduce the two cyclopentanes tereocenters in as ingle step. The use of a furan substituent allows ah igh trans diastereoselectivity to be achieved duringt he radicalp rocess and it contains the four carbona toms C1-C4 of the natural product in an oxidation state closely relatedt ot he one of the target molecule. The eight-step synthesis requires six product purifications and it provides (+ +)-brefeldin Ci n1 8% overall yield.[**] Ap revious versiono ft his manuscript has been deposited on ap reprint server (https://doi.org/10.26434/chemrxiv.8397731.v1)Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.Scheme3.Conversion of alkyne 2b into (+ +)-brefeldin C. X-ray single-crystal structureof(+ +)-brefeldin C( 50 %p robability ellipsoids).

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Di-t-butyl Hyponitrite

Cited by 14 publications

References 52 publications

Methyl Radical Initiated Kharasch and Related Reactions

Methyl Radical Initiated Kharasch and Related Reactions

Methyl Radical Initiated Kharasch and Related Reactions

A Short Synthesis of (+)-Brefeldin C via Enantioselective Radical Hydroalkynylation

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