Hydrogenolysis, of phenolic ethers to aromatics

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... 

Catalytic hydrogenation in acetic anhydride-benzene removes the aromatic benzyl ether and forms a monoacetate hydrogenation in ethyl acetate removes the aliphatic benzyl ether to give, after acetylation, the diacetate. Trisubstituted aDcenes can be retained during the hydrogenolysis of a phenolic benzyl ether. ... 

The section on the cleavage of alkyl henzyl ethers should he consulted, since many of those methods are applicable to phenolic benzyl ethers. It should he noted that phenolic benzyl ethers can be retained during the hydrogenation of olehns and the hydrogenolysis of the Cbz group hy the addition of 2,2 -dipyridyl as an additive. There is also a solvent dependence with aromatic solvents allowing... 

Fig (12) Transformation of keto ester (94) to (96) is described. Michael addition leads the formation of the adduct (97) which is subjected to cyclization, aromatization and hydrogenolysis to obtain the phenol (99). This on diazotization, methylation and reduction afforded the amino ether (100). Further diazotization, methanolysis and saponification produce ethyl (+)-camosic acid dimethylether (102). 

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