Rearrangement alkyl phenyl ethers

Nafion-H is also very efficiently catalyzes the rearrangement of anisole, methy-lanisoles, and phenetole to ring-alkylated phenols and products of transalkylation when vapors of the alkyl aryl ethers are passed over it at temperatures higher than 160°C. At these reaction temperatures, some of the starting alkyl phenyl ethers... 

The thermal rearrangement of allyl ethers is a process entirely different from. the rearrangement of saturated alkyl phenyl ethers by acidic catalysts.103 The latter process seems to be intermolecular, gives consider-... 

Tateiwa, J. I., T. Nishimura, H. Hiriuchi, and S. Ulmura. 1994b. Rearrangement of alkyl phenyl ethers to alkylphenols in the presence of cation-exchanged montmorillonite (Mn" -mont)../. Chem. Soc. Perkin 3367-3371. 

The rearrangement reaction of a variety of alkyl phenyl ethers over a dealumi-nated HY zeolite has been shown to involve both intramolecular and intermolecular processes to afford phenol, (alkoxyalkyl)benzenes and alkylphenols as the main products. o-Benzylphenol has been obtained as the exclusive product in the rearrangement of benzyl phenyl ether in the presence of montmorillonite. The mechanism for a novel zeolite /3-catalysed rearrangement of alkoxybenzyl allyl ethers to aldehydes and ketones has been investigated by the use of cross-over reactions and deuterium labelling. The reaction was found to be mainly intramolecular and has been described as a nucleophilic attack of the double bond on the electrophilic benzylic carbon of the ether-Lewis acid complex, followed by a... 

Alkylation of phenols and rearrangement of phenyl ethers. 4-Hydroxybu-tanone serves as an alkylating agent, giving 4-(4-hydroxyphenyl)-2-butanone in 28% yield on heating with phenol in the presence of Zr(IV)-montmorillonite at 100°C for 48 h. The same compound is obtained in 34% yield when 3-oxobutyl phenyl ether is treated with Zn(II)-montmorillonite and phenol. ... 

For example /-butyl phenyl ether with aluminium chloride forms para-t-butyl phenol155. Often the de-alkylated phenol is also formed in considerable quantity. The reaction formally resembles the Fries and Claisen rearrangements. Like the Fries rearrangement the question of inter- or intramolecularity has not been settled, although may experiments based on cross-over studies156, the use of optically active ethers157 and comparison with product distribution from Friedel-Crafts alkylation of phenols158 have been carried out with this purpose in view. 

R2NC1, 91, 92 phenyl acetate, Fries rearrangement of, 475 phenyacetyl halides, acylation by, 173 2-phenylbenzoic acid, cycliacylation, 185 phenyl ethers, alkylation of, 149 —, bromination of, 130 —, hydrogen exchange with, 260 —, rearrangement of, 476 phenyl ethyl mercury, mercuridemercuration of, 359, 360... 

Some allyl phenyl ethers with an alkyl substituent on the end carbon of the allyl group rearrange to give the normal ortho-Claisen product together with another isomeric O-allyl phenol. The latter, formed by the rearrangement of the normal product, has been established. This is called abnormal Claisen rearrangement, is illustrated by the following example. 

RSeCJIi — ROCHi. Oxidation of an alkyl phenyl selenide with m-chloroperben-zoic acid (2-5 equiv.) in methanol affords the corresponding alkyl methyl ethers in high yield. Oxidation of selenides with a vicinal phenyl group is accompanied by rearrangement of the phenyl group. vtc-Methoxy selenides derived from cycloalkenes are oxidized under these conditions to dimethyl acetals of ring-contracted aldehydes. 

Boron trifluoride catalyzes the condensation of phenol and propylene to isopropyl phenyl ether and the subsequent rearrangement of this compound to o-isopropyl phenol. This rearrangement of an aryl alkyl ether is similar to the Fries reaction of phenolic esters (method 209). 

Allyl phenyl ethers undergo an intramolecular [3,3]-sigmatropic rearrangement (the Claisen rearrangement) to form the C-alkyl derivative (Scheme 4.18). A consequence of the electrocyclic mechanisms is that the y-carbon atom of the allyl ether becomes attached to the aromatic ring. 

Alkyl and benzyl aryl ethers undergo acid-catalysed rearrangement to afford phenols. For instance, benzyl phenyl ether under treatment with AlBrs in dichloromethane yields exclusively 2-benzylphenol with simultaneous production of phenol. The ratio of phenol and 2-benzylphenol is hardly affected by the solvent. Other type of catalysts have also been used successfully in this type of rearrangement. For instance, trifluoroacetic acid converts 4-(2 -methyl-but-2 -yl)phenyl benzyl ether (205) to the corresponding phenol 206 (equation 136) and over montmorillonite clays, benzyl phenyl ether (207), is converted to 2-benzylphenol (208) (equation 137) . 

As shown by the examples in Table 1, the ring opening of carbonyl-substituted alkylcy-clopropanes is a general process. In fact, this isomerization has been shown to be part of the so-called enol-ene rearrangement which itself involves interchange of the ) - and <5-carbon atoms of ]S-alkyl-y,(5-unsaturated carbonyl systems, and which is also involved in the so-called abnormal Claisen rearrangement of y-alkylallyl phenyl ethers. ... 

Ethyl or longer-chain phenyl ethers, in addition, would produce an ion of m/z 94 (C6H60+ ) via McLafferty-type rearrangement [reaction (6.29)]. The ion of m/z 93 (C6H7N+) is also prodnced from ionized 2-alkyl and 4-alkylpyridines via the McLafferty rearrangement. The m/z 105 ion (CeHsCO" "), which is produced via a-cleavage, is evidence for the presence of phenyl ketones and esters and amides of benzoic acids. Esters of benzoic acids will also produce a characteristic ion of m/z 122 as a result of the McLafferty rearrangement ... 

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