Benzoates, rearrangement

Plus 20% of three mono-O-benzyl derivatives with the benzoates rearranged. 

Copper(I) salts catalyze the allylic oxidation of alkenes in the presence of peresters, such as tert-BuOjCOPh, to afford the corresponding allylic benzoate esters. In the case of terminal alkenes, internal allylic esters are formed in preference over the terminal isomers. The mechanism is believed to involve addition of an allylic radical to copper(II) benzoate. " Rearrangement of the copper(III) intermediate then produces the product and regenerates the copper(I) catalyst. 

Deuterium-labelling studies applied to the acetolysis of the 3,5-dinitrobenzoate ester of the tricyclic alcohol (150) indicate that the dihydroindenylenol acetate (151) derives from a second product of reaction, the allylic acetate (152), by way of the intermediate ester (153) which subsequently suffers thermal fission. Skeletally unrearranged acetates together with (152) are formed initially from (150)-3,5-dinitro-benzoate rearrangement to (151) occurs at the higher reaction temperatures and prolonged reaction times. 

Conversion of 5-allylthioimidates into /V-allylthioamides is catalyzed by Pd(Il). 2-Allylthiopyridine (820) is converted into the less stable l-allyl-2-thio-pyridone 821 owing to Pd complex formation[509], Claisen rearrangement of 2-(allylthio)pyrimidin-4-(3//)-one (822) affords the A-l-allylation product 823 as the main product rather than the A -3-allylation product 824[510] The smooth rearrangement of the allylic thionobenzoate 825 to the allyl thiolo-benzoate 826 is catalyzed by both PdCl2(PhCN)2 and Pd(Ph3P)4 by different mechanisms[511],... 

Benzoates (by double hydrogen rearrangement) (The ester must be ethyl or higher.)... 

Photolysis reactions often are associated with oxidation because the latter category of reactions frequently can be initiated by light. The photooxidation of phenothiazines with the formation of N- and S-oxides is typical. But photolysis reactions are not restricted to oxidation. In the case of sodium nitroprusside, it is believed that degradation results from loss of the nitro-ligand from the molecule, followed by electronic rearrangement and hydration. Photo-induced reactions are common in steroids [36] an example is the formation of 2-benzoylcholestan-3-one following irradiation of cholest-2-en-3-ol benzoate. Photoadditions of water and of alcohols to the electronically excited state of steroids have also been observed [37],... 

Although the Wolf rearrangement of diazoketones in the presence of silver benzoate and triethylamine in methanol could involve rearrangement of an intermediate diradical or carbonium ion conjugate... 

The reaction goes faster in more polar solvents (a range of 106 in the rate constant) and parallels carbonium ion rearrangements in that respect. The effect of substituents in the para position of the benzoate group also suggests that the rate-determining step is the formation of an initial ion pair. The reaction is faster with the nitro than with the methoxyl substituent.819 820 The Hammett p value is 1.34. The activation parameters are not known for any but the unsubstituted member of the series however, and hence it is not known to what extent the relative rates depend upon the temperature. 

Aldehyde 54 and the hydroxamic acids 55 were generated together in an acid-catalysed elimination reaction (Scheme 7 pathway (ii)). A crossover experiment indicated that esters are formed in a concerted rearrangement concomitant with the likely formation of the hydroxynitrene 57 (Scheme 7 pathway (iii)) while there is no evidence to date for the formation of hydroxynitrene, joint solvolysis of equimolar quantities of /V-acetoxy-/V-butoxy-/>-chlorobenzamide 26e and N- acetoxy-/V-benzyloxybenzamide 27a afforded significant quantities of butyl p-chlorobenzo-ate (36%) and benzyl benzoate (54%) as the only esters. This is an example of a HERON reaction, which has been identified in these laboratories as a characteristic rearrangement of bisheteroatom-substituted amides.32,33,42 43 155 158 Since ester formation was shown to prevail in neutral or low acid concentrations, it could involve the conjugate anion of the hydroxamic acid (vide infra).158... 

Initially, a reaction of A-acetoxy-A-butoxybenzamide 25c with A-methyl aniline 61 in butyl benzoate 63(R = Bu) and acetic acid. Close examination of these highly coloured reaction mixtures indicated the presence of crystals of A,A-dimethyl-A,A-diphenyltetrazene 65 (Scheme 11, R = Bu). The reaction is promoted by polar solvents as reactants are unchanged in pure acetonitrile. A crossover experiment using a mixture of /V- a ce t o x y - A-- b u t o x y - to 1 u a m i d e 26d and A-acetoxy-A-ethoxybenz-amide 25a afforded clean yields of butyl /Moluatc and ethyl benzoate thus pointing to an intramolecular rearrangement.41... 

With ligand 170 (R = Bn), Fahmi reports the formation of an equal amount of byproduct, formulated as the allylic imide 171, Eq. 103. Indeed, Fahmi suggests that this is the correct structure of the same byproduct observed by Katsuki et al. (116) (cf. Section III.A.4, Structure 161). Fahmi suggests that this product may be formed by insertion of solvent in copper benzoate intermediate 172, as illustrated in Scheme 12. The generated copper imidate 174 then reacts with the allylic radical and combines to provide the allylic amination product 175 that rearranges to the observed imide 171. 

Solvent polarity has a strong influence on the yield of rearranged products as indicated in Table 1 for the PFR of phenyl benzoate (14) in several solvents [31]. Polar solvents favor the rearrangement, whereas nonpolar solvents favor phenol formation. An experiment carried out with methanol-ether mixtures... 

Aroylcoumaran-3-ones (61) can also be synthesized from the Baker Venkatraman rearrangement of 2-[(tosyloxy)acetyl]phenyl benzoates with potassium hydroxide (920PP469, 92S629). 

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