Mechanism of the reaction of diazomethane with weak acids

Kreevoy, Maurice M.; Thomas, Stephen J.

doi:10.1021/jo00444a050

Cited by 9 publications

(3 citation statements)

References 5 publications

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“…Several mechanisms involving carbene intermediates were suggested for the etherification of alcohols with diazo compounds . For acidic alcohols such as phenols it was suggested that protonation of the diazomethane gives the methyldiazonium ion which reacts with the nucleophile to give the ether . When applied to our nonaqueous reaction system, the acidic enol (ROH) protonates CH 2 N 2 to CH 3 N 2 + (eq 11, step a) which then reacts with the enolate ion nucleophile (eq 11, step b)…”

Section: Resultsmentioning

confidence: 99%

Reactions of Enols of Amides with Diazomethane

Lei

Rappoport

2002

J. Org. Chem.

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The reaction of 10 carboxamides activated by two beta-electron-withdrawing groups, which mostly exist completely or partially in their enol forms, with diazomethane was investigated. The main outcome is the diversity of reactions observed. With the most acidic enols 3-7, activated by at least one trifluoroethoxycarbonyl group or a cyano group, O-methylation or O,N-dimethylation takes place. With beta-dimethoxycarbonyl-activated systems 5 and 8, the C-methylation product of the amide form was one of the products. With a Meldrum's acid anilide enol 2, a cleavage took place leading to the C-alkylated imine having a CH(CO(2)Me)(2) group. Exchange of one 2,2,2-trifluoroethoxycarbonyl by a methoxycarbonyl in the C,N-dimethylation product of Me(2)CHNHC(OH)[double bond]C(CO(2)CH(2)CF(3))(2) 4 took place. The 2-anilido-1,3-cyclopentanedione 10 was methylated on a ring carbonyl while the enol of the 1,3-indanedione analogue 11 reacted with three diazomethane molecules and underwent a ring expansion and O-methylation to the 3-anilido-1,4-dimethoxynaphthalene. It is suggested that the reaction initiates by protonation of the diazomethane by the enol and an approximate qualitative relationship exists between the acidity of the enol and K(enol) and the regioselectivity of the reaction.

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Section: Resultsmentioning

confidence: 99%

Reactions of Enols of Amides with Diazomethane

Lei

Rappoport

2002

J. Org. Chem.

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“…Perhaps the most well-known example of esterification by symbiotic activation is the reaction of carboxylic acids with diazoalkanes (like 1 , Figure ). These transformations have been shown to proceed through a tight ion pair intermediate that is formed after proton transfer from the carboxylic acid and generate only unreactive nitrogen gas as a side product. Unfortunately, many diazoalkanes have a reputation as being toxic and energetic, limiting their use and often forcing researchers to form these reagents in situ to avoid issues with handling .…”

Section: Introductionmentioning

confidence: 99%

Ester Formation via Symbiotic Activation Utilizing Trichloroacetimidate Electrophiles

et al. 2019

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Trichloroacetimidates are useful reagents for the synthesis of esters under mild conditions that do not require an exogenous promoter. These conditions avoid the undesired decomposition of substrates with sensitive functional groups that are often observed with the use of strong Lewis or Brønsted acids. With heating, these reactions have been extended to benzyl esters without electron donating groups. These inexpensive and convenient methods should find application in the formation of esters in complex substrates.

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“…The isotope effect would then be given by, kH20/kD20= 4HA/@A$p (4s)'. (3) Here @ A is the product of the fractionation factors of the solvation shell of A-(i.e. the transfer activity coefficient of A-from H 2 0 to D20 [25]), and &A is for the acid proton indicated in the Scheme.…”

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confidence: 99%

Substituent and Isotope Effects on the Hydrolysis Rates of 2‐Aryl‐2‐diazocarboxylic Esters

Bui‐Nguyen

Dahn

McGarrity

1980

Helvetica Chimica Acta

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SummaryThe overall kinetic solvent isotope effects on the acid catalyzed hydrolysis of a series of 2-aryl-2-diazocarboxylic esters ArCN2COOCH3, and one 2-aryl-2-diazocarboxamide C6H5CH2CON (CH,), vary inversely with the reactivity of the substrate, between limits of 3.14 and 1.46. A linear Hammett plot for the hydrolysis rates of the a-diazocarboxylic esters indicates that there is no mechanistic change for the hydronium-ion-catalyzed reaction. The relation between hydrolysis rate and buffer acid concentration deviates from linearity for high values of the latter. It is shown on the basis of the solvent isotope effects for the non-linear region that this deviation does not stem from a mechanistic change caused by the buffer base component. The specific salt effects on the general acid-catalyzed reaction are discussed.

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Mechanism of the reaction of diazomethane with weak acids

Cited by 9 publications

References 5 publications

Reactions of Enols of Amides with Diazomethane

Reactions of Enols of Amides with Diazomethane

Ester Formation via Symbiotic Activation Utilizing Trichloroacetimidate Electrophiles

Substituent and Isotope Effects on the Hydrolysis Rates of 2‐Aryl‐2‐diazocarboxylic Esters

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