O-Derivatives of 1,2-Dihydroxy Compounds

Reactions of the hydroxyl group in this group of compounds comprise chlorocarbonylation, its reduction, substitution by an alkyl group, and methylation, as shown in the following examples. 

Moderately pure 2-isopropoxyphenol, containing a small amount of triphenylphosphonium choride, when gradualy treated at 118-150°C with phosgene afforded 2-isopropoxyphenyl chloroformate in 97% yield with recoverable starting material (ref.66). 

Electrochemical dehydroxylation of 2-methoxyphenol by way of the diethyl phosphate, prepared by standard procedures, in dimethylformamide containing tetraethylammonium 4-toluenesulphonate as supporting electrolyte in a divided cell (at -2.6 to -2.7 volts) gave anisole in 61% yield (ref.67). 

Replacement of the hydroxyl group in 2-methoxyphenol by an n-butyl group was achieved in the following way. To Li2Cu(CN)Bu2, prepared by dropwise addition of n-butyllithium in tetrahydrofuran at -78 C to cuprous cyanide in tetrahydrofuran and warming of the mixture to -20°C, 2-methoxyphenyl trifluoromethanesulphonate in tetrahydrofuran was gradually added after the reagent mixture had been recooled to -70°C. Reaction was completed over 40 hours at -20 C to afford 2-n-butylanisole in 50% yield (ref.68). 

Morphine in toluene solution containing potassium carbonate and trimethylphenylammonium chloride followed by stirring of the mixture at 45-120°C during 25 hours gave, after removal of toluene, acidification to pH 5 and removal of dimethylaniline, codeine in 99% yield (ref.69). There is an element of rediscovery in this since the author recalls an exactly similar method being investigated successfully in 1945 by May and Baker Ltd. (now Rhone Poulenc). 

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