Mechanism of the copper-catalyzed addition of diazoalkanes to olefins. I. Steric effects

Moser, William R.

doi:10.1021/ja01033a017

Cited by 132 publications

(44 citation statements)

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“…Cu(II)-complexes are applicable as well, but need to be reduced in-situ since Cu(I) is the active species 70 in carbene reactions. This can be achieved by treatment with DIBAL-H, substituted hydrazines, or the diazo agent itself.…”

Section: Scheme 15mentioning

confidence: 99%

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Enantioselective synthesis of (−)-paeonilide

Harrar

Reiser

2012

Chem. Commun.

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Section: Scheme 15mentioning

confidence: 99%

“…64 was also used as starting material for the total synthesis of paraconic acids, 40 i.e. roccellaric acid (69), 41 nephrosteranic acid (70) and protopraesorediosic acid (71). Methylenolactocin (73) and protolichesterinic acid (72) were accessed in a formal total synthesis.…”

mentioning

confidence: 99%

Enantioselective synthesis of (−)-paeonilide

Harrar

Reiser

2012

Chem. Commun.

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“…The influence of the olefin is the weakest, while the electronic influence of the transition metal provides the dominant regio-and stereochemical control. Studies with chiral catalysts confirmed (21)(22)(23)(24) that the transition metal is directly involved in the product-forming step. The more stable trans cyclopropanes usually predominate and the stereoselecCan.…”

Section: Discussionmentioning

confidence: 94%

Dihydrofurans from α-diazoketones due to facile ring opening – cyclization of donor–acceptor cyclopropane intermediates

Lund¹,

Kennedy²,

Fallis³

1996

Can. J. Chem.

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A series of a-diazoketones, 8, 25,28,31, and 34, have been synthesized and their reaction with ethyl vinyl ether examined under various reaction conditions. In the presence of metal salts (Rh,(OAc),, Pd(OAc),, CuC1) the ethoxydihydrofurans 12,37,39,41, and 43 are produced. Sensitized irradiation of the a-diazoketone 8 afforded the dihydrofuran 12 plus cyclobutanone 7, while direct photolysis of a-diazoketones 8,25,28,31, and 34 gave the cyclobutanones 7,38,40,42, and 44, respectively. A sample of the cyclopropylketone 45 was isolated from the rhodium(I1) acetate mediated reaction of 34 and its facile rearrangement to dihydrofuran 43 demonstrated. Collectively, these results indicate that the initial product from the reaction of an a-diazoketone with an electron-rich alkene such as ethyl vinyl ether is a cyclopropylketone. The donnor-acceptor substitution pattern of this intermediate results in spontaneous rearrangement to a dihydrofuran. Thus a direct dipolar cycloaddition mechanism is not involved when a-diazoketones react with en01 ethers under metal-mediated conditions. Instead, these reactions follow a cyclopropanation rearrangement or, more accurately, cyclopropanation -ring opening -cyclization pathway.Key words: diazoketone, rhodium acetate, dihydrofuran, cyclopropylketone, vinyl ether.RCsumC : On a synthttist une strie d'a-diazocttones 8,25,28,31 et 34 et on a ttudit, dans difftrentes conditions, leur rtaction avec l'tther tthylvinylique. En prtsence de sels mttalliques (RH,(OAc),, Pd(OAC),, CuC1) on obtient les tthoxydihydrofurannes 12,37,39,41 et 43. L'irradiation sensibiliste de l'a-diazocttones 8 produit le dihydrofuranne 12 et la cyclobutanone 7, tandis que la photolyse directe des a-diazocttones 8,25,28,31 et 34 donne les cyclobutanones 7,38,40,42 et 44 respectivement. On a isolt un tchantillon de cyclopropylcttone 45 de la rtaction du compost 34 en prtsence de l'acttate de rhodium et on dtmontre sa transposition facile en dihydrofuranne 43. Collectivement, ces rtsultats indiquent que le produit initial de la rtaction d'une a-diazocttone avec un alcbne riche en tlectrons tel l'tther Cthylvinylique est une cyclopropylcttone. Le modble de substitution donneur-accepteur de cet intermtdiaire provient d'une transposition spontante en dihydrofuranne. Ainsi un mCcanisme de cycloaddition dipolaire directe n'est pas impliqut lorsque une a-diazocttone rtagit avec des tthers tnoliques en prtsence d'un mCtal. Au lieu de cela ces rtactions suivent une transposition cyclopropanique ou plus prtcistment un processus de cyclopropanation, d'ouverture du cycle du cyclopropane et de cyclisation.Mots cle's : diazocttone, acttate de rhodium, dihydrofuranne, cyclopropylcCtone, tther vinylique.[Traduit par la rtdaction]

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“…Then, the yield of cyclopropanes goes up slowly with the prolonged reaction and the yield of dimers decreases concurrently. In literatures [28] and [29], it is suggested that copper(II) is reduced to the copper with lower valence at the beginning of the reaction (see Scheme 3) and that this copper with lower valence shows Scheme 3. CuO was reduced to copper species with lower valence by a trace amount of N 2 CHR at the beginning of the reaction.…”

Section: Reaction Mechanismmentioning

confidence: 99%

“…CuO was reduced to copper species with lower valence by a trace amount of N 2 CHR at the beginning of the reaction. high activity for cyclopropanation reactions [28,29]. However, almost all the dimers are produced within the first few minutes.…”

Section: Reaction Mechanismmentioning

confidence: 99%