122948-44-1Relevant articles and documents
The Heck-type arylation of allylic alcohols with arenediazonium salts
Masllorens, Judit,Bouquillon, Sandrine,Roglans, Anna,Hénin, Fran?oise,Muzart, Jacques
, p. 3822 - 3826 (2007/10/03)
The Heck coupling of ArN2BF4 with secondary allylic alcohols, carried out in methanol using Pd(dba)2 as catalyst without extra ligands and base, leads to the corresponding β-arylated carbonyl compounds. Such conditions afford arylated acetals from primary allylic alcohols.
Lifetimes of Oxocarbenium Ions in Aqueous Solution from Common Ion Inhibition of the Solvolysis of α-Azido Ethers by Added Azide Ion
Amyes, Tina L.,Jencks, William P.
, p. 7888 - 7900 (2007/10/02)
Rate constants for hydration of the oxocarbenium ions derived from a series of carbonyl compounds have been determined from common ion inhibition of the solvolysis of the corresponding α-azido ethers by trapping of the oxocarbenium ion intermediate with added azide ion, assuming kaz = 5E9 M-1s-1: acetophenone, kHOH = 5E7; acetone, 1E9; 4-methoxybutanone, 2E9; methoxyacetone, 4E9; benzaldehyde, 2E9; propionaldehyde, 2E10 s-1.Substitution on the reacting carbon atom affects log kHOH 0.4 as much as log Keq.Resonance effects are much larger than polareffects of substituents on kHOH, compared with Keq; this represents imbalance in the expression of these effects in the transition state.Use of these substituent effects to estimate the lifetime of glycosyl and methoxymethyl oxocarbenium ions gives values of kHOH ca. 1E12 s-1 for the glycosyl cation and 1E12-1E15 s-1 for the methoxymethyl cation.It is concluded that the glycosyl cation has a short but significant lifetime in aqueous solution and that there is little or no barrier for hydration of the methoxymethyl cation.The effects of substituents on the rate constants for addition to oxocarbenium ions are smaller than those for addition to the corresponding carbonyl compounds.The decrease in reactivity toward water of protonated acetone compared with the corresponding oxocarbenium ion by ca. 1E5 suggests that the proton occupies an intermediate position between the carbonyl group and water.The dependence of log kROH on pKROH for the addition of alcohols to oxocarbenium ions derived from derivatives of butanone and propionaldehyde in aqueous alcohol mixtures follows slopes of 0.5 and 0.1, respectively.
