Correlations between catalytic reactions of diazo compounds and stoichiometric reactions of transition-metal carbenes with alkenes. Mechanism of the cyclopropanation reaction

Doyle, Michael P.; Griffin, John H.; Bagheri, Vahid; Dorow, Roberta L.

doi:10.1021/om00079a011

Cited by 187 publications

(99 citation statements)

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“…In this case, 1,3 ring closure to 66 is disfavoured with respect to the 1,5 ring closure. The stabilization of the dipolar intermediate is consistent with Doyle's mechanism where an increase in the nucleophilicity of the enolate oxygen increases the ease of 1,scyclization compared to 1,3-cyclization (6).…”

Section: Discussionsupporting

confidence: 82%

“…However, the product was a new methoxydihydrofuran system that differed from the dihydrofuran 12 by more than the substitution pattern. The 'H NMR signal at 6 Table 2. In addition, it was not the product 57 from closure of the oxygen anion on the sulfinyl bearing carbon.…”

Section: Resultsmentioning

confidence: 99%

“…by Doyle et al (6,20,25) to occur through an initial interaction between the olefinic T bond and the electrophilic centre of the metal carbenoid, followed by a-bond formation with backside displacement of the catalyst (Scheme 10). As the reaction proceeds the T-complexed olefin may rotate around the electrophilic centre to place the C-C bond of the olefin parallel to the metalkarbon bond.…”

Section: Discussionmentioning

confidence: 99%

“…For example, the spirosystem 14 may be isolated, but the related cyclopropane 1 5 was not detected when dimethyl diazomalonatereacted in the presence of copper with 1-methoxycyclohexene (5). Other methoxy cyclopropanes also rearranged more readily than the corresponding ethoxy-substituted derivatives (6). However, the reaction conditions markedly influence the course of diazocarbonyl rearrangements, particularly solvent polarity (pentane versus CH,Cl,) (7) and the catalyst (Rh,(OAc), versus Rh,(OPiv),) (8).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionsupporting

confidence: 82%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…Em algumas reações não é possível isolar-se o ciclopropano intermediário obtendo-se diretamente o diidrofurano 3q,r . No Esquema 22 estão apresentados vários diidrofuranos 83 49 , 85 50 , 87 51 , 89 52 , 91 53 e 93 54 obtidos a partir de reações com enóis éteres cíclicos e os diidrofuranos 95 52 , …”

Section: Aplicações De Compostos Diazo Carbonílicos Nas Sínteses De Dunclassified

Compostos alfa-diazo carbonílicos: uma estratégia atraente para a síntese orgânica

Ferreira¹,

Pereira²,

Souza³

et al. 2001

Quím. Nova

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Chromium Complex Catalyzed Synthesis of Spirocyclopropanes from Diaryl Diazo Compounds – Direct NMR-Spectroscopic Observation of a Carbene Complex Intermediate

Pfeiffer

Nieger

Dötz³

1998

Eur. J. Org. Chem.

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Correlations between catalytic reactions of diazo compounds and stoichiometric reactions of transition-metal carbenes with alkenes. Mechanism of the cyclopropanation reaction

Cited by 187 publications

References 0 publications

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

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

Compostos alfa-diazo carbonílicos: uma estratégia atraente para a síntese orgânica

Chromium Complex Catalyzed Synthesis of Spirocyclopropanes from Diaryl Diazo Compounds – Direct NMR-Spectroscopic Observation of a Carbene Complex Intermediate

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