Phenolic ethers rearrangement

Oxidative Coupling of Phenols and Phenol Ethers Rearrangement Reactions... 

Claisen rearrangement (Section 24 13) Thermal conversion of an allyl phenyl ether to an o allyl phenol The rearrange ment proceeds via a cyclohexadienone intermediate... 

AHyl phenyl ethers rearrange cleanly at high temperatures, producing o-aHyl phenols or -aHylphenols if both ortho positions are blocked. This reaction is called the Claisen rearrangement (10). 

Thioamide formation benzodiazepinone, 505 heteiodiazepinone, 621 phosphorus pentasulf ide, 323, 600 Thioazole formation, nitrile addition, 301 Thiocarbamate formation, 588 phenol, 95 rearrangement, 517 Thioenol ether formation, 185, 517 addition-elimination, 554 Thioester formation, mixed anhydride, 184 Thioether formation, 241, 300, 413, 416 alkylation, 586, 588 aromatic displacement, 416 Thiohydantoin formation, 293 Thiol interchange, benzothiazole formation, 422... 

Rearrangement of Phenolic Ethers 1/C-Hydro,5/0-alkyl-interchange... 

Phenolic ketones may be prepared by the Hoesch acylation reaction, which may be regarded as an extension of the Gattermann aldehyde synthesis (Section 6.10.1, p. 990). The procedure involves reaction of a nitrile with a phenol (or phenolic ether) in the presence of zinc chloride and hydrogen chloride best results are usually obtained with polyhydric phenols or their ethers, as for example in the preparation of phloroacetophenone (Expt 6.125). The formation of phenolic ketones by means of the Fries rearrangement of phenolic esters with aluminium chloride is discussed on p. 976. 

Substituted allyl aryl ethers undergo a Claisen rearrangement similar to the reaction described in text Section 24.13 for allyl phenyl ether. 2-Butenyl phenyl ether rearranges on heating to give o-( 1-methyl-2-propenyl)phenol. 

Allyl ethers of enols and phenols undergo rearrangement to C-allyl derivatives when heated to sufficiently high temperatures. The reaction, named after its discoverer (Claisen, 1912), was first observed when ethyl O-allylacetoacetate was subjected to distillation at atmospheric pressure in the presence of ammonium chloride.1 2... 

The crotyl ether of the same phenol also rearranges without inversion.8 The only known example of para rearrangement accompanied by inversion is the reaction of a-ethylallyl 2-carbomethoxy-6rmethylphenyl ether (V), which yields the p-(y-ethylallyl) derivative (VI).8... 

Behr et al. [114] investigated the selective formation of octadienyl phenol ethers in a liquid-liquid biphasic loop reactor. Although the Pd/TPPTS system showed good activity and selectivity (86% conversion with 74% selectivity towards the telomer after 5 h) in a lab-scale batch reactor, telomer yields in the loop reactor were insufficient for efficient phase separation. Telomerization with phenol was therefore deemed unsuitable for this type of reactor. The authors also noted that the C-allylated octadienyl phenol product rather than the telomerization product became the main product after 6 h of reaction, attributing this to a metal-catalyzed Claisen-type rearrangement. 

Electron transfer from oxygen to copper gives a phe-noxyl radical, which couples with another copper-bound radical to form the C—O—C dimer and Cu(I). The reaction behaves as a step reaction rather than a chain reaction. A quinol ether rearrangement occurs to equilibrate polymer and monomer. High-molecular-weight polymer is formed only in the late stages of reaction. Indeed, other phenols are incorporated into the polymer if they are added at the end of the reaction because of the quinol ether rearrangement. 

Copper compounds are catalysts for the Michael addition reaction (249), olefin dimerizations (245, 248), the polymerization of propylene sulfide (142), and the preparation of straight-chain poly phenol ethers by oxidation of 2,6-dimethylphenol in the presence of ethyl- or phenyl-copper (209a). Pentafluorophenylcopper tetramer is an intriguing catalyst for the rearrangement of highly strained polycyclic molecules (116). The copper compound promotes the cleavage of different bonds in 1,2,2-tri-methylbicyclo[1.1.0]butane compared to ruthenium or rhodium complexes. Methylcopper also catalyzes the decomposition of tetramethyllead in alcohol solution (78, 81). 

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). 

Reaction of the hydrocarbons in this series with phenols or phenol ethers in the presence of suitable catalysts is well known, a-fenchene and phenol yielding a mixture of o- and p-isofenchylphenols in the presence of aluminium phen-oxide practically the same reaction was described seven years ago. Reaction of camphene with a phenol ester in the presence of stannic chloride is reported to give a bornyl compound, but terpenoid rearrangements are notorious under such conditions, and it is doubtful whether this is the only product. 3,3-Dibromocamphor (261) has been converted into substituted cyclo-hexanecarboxylic acids by the route shown in Scheme 13. ... 

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