Hydrogenolysis of phenols

Hydrogenolysis, of phenolic ethers to aromatics, 51, 85 of p-(1-phenyl-5-tetrazoly-loxy)biphenyl with palladium-on-charcoal catalyst to biphenyl, 51, 83... 

Distillation of phenols with zinc dust [617] or with dry lithium aluminum hydride [618] also results in hydrogenolysis of phenolic hydroxyls but because the reaction requires very high temperatures hardly any other function in the molecule can survive, and the method has only limited use. 

DEHYDROXYLATION OF PHENOLS HYDROGENOLYSIS OF PHENOLIC ETHERS BIPHENYL... 

Bagnell LJ, Jeffery EA. Electrolytic hydrogenation and hydrogenolysis of phenols at platinum black electrodes. Aust J Chem 1980 33 2565-2569. 

Table 6 shows results of hydrogenolysis of phenols by all four methods described above. 

Table 6 Comparison of Results of Hydrogenolysis of Phenols after their Conversion to S-Aryloxy-1-phenyltetrazoles (A), 2-Aryloxybenzoxazoles (B), O-Aryl-NJV- diethylisoureas (C), and 0-Ary -NfT-...

A new synthesis of 5-chloro-l-phenyltetrazole, a useful activating group for the hydrogenolysis of phenols, was reported using NCS-mediated chemistry. The phase-transfer reaction of NCS with sodium azide in chloroform generates chloroazide in situ. The transient chloroazide reacts with phenyl isocyanide via a 1,3-dipolar cycloaddition at 0 °C to afford 5-chloro-l-phenyltetrazole in 69% yield (eq 30). ... 

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