2.4.6- Trimethyl-phloroglucinol

The reaction of 1,3,5-tribromobenzene with excess sodium methoxide in methanol—NJV-dimethylformamide and in the presence of a catalytic amount of cuprous iodide gives ca 90% yield phloroglucinol trimethyl ether (1,3,5-trimethoxybenzene). The latter is hydrolyzed with 35 wt % hydrochloric acid at room temperature to give a 90% yield of phloroglucinol (140—142). 

Phloroglucinol, AH08 Phloroglucinol trimethyl ether, AP80... 

Preparation by Friedel-Crafts acylation of phloroglucinol trimethyl ether with benzoyl chloride in the presence of aluminium chloride [753], in ethyl ether for 8 h [416]. 

Preparation by reaction of m-hydroxyben- / zonitrile with phloroglucinol trimethyl... 

Obtained by reaction of 3,5-dimethoxy-benzoyl chloride with phloroglucinol trimethyl ether in ethyl ether in the presence of aluminium chloride at 25° for 48 h (16%) [167],... 

Obtained by reaction of veratronitrile with phloroglucinol trimethyl ether (Hoesch reaction) (15%) [439]. 

Also obtained (major product) by reaction of acetyl chloride on phloroglucinol trimethyl ether with aluminium chloride in boiling petroleum ether [3086],... 

Also obtained by reaction of acetic add with phloroglucinol trimethyl ether in the presence of PPA on a boiling water bath for 5-20 min (76%) [4061]. 

Preparation by reaction of bromoacetyl bromide with phloroglucinol trimethyl ether according to [4509], but using aluminium bromide instead of aluminium chloride in carbon disulfide at r.t. [4508]. 

Also obtained (by-product) by Friedel-Crafts acylation of phloroglucinol trimethyl ether with acetyl chloride in the presence of aluminium chloride in boiling carbon disulfide [5819]. N.B. No direct proof of the constitution of the diketone was described, bnt it wonld appear most probable that it is 3-acetyl-6-hydroxy-2,4-dimethoxyacetophenone [5819]. 

Also obtained by reaction of propionitrile with phloroglucinol trimethyl ether [7515]. 

A unique feature of this procedure is the selective monode-methylation of the dimethyl ether. The scope of this reaction is illustrated6 in part by the preparation in high yield of p-methoxyphenol, guaiacol, and phloroglucinol dimethyl ether from the respective fully O-methylated compounds. An exception is pyrogallol trimethyl ether which affords pyrogallol 1-monomethyl ether in high yield.6... 

Dimethyl-4-pyrimidone and l,4,6-trimethyl-2-pyrimidone show similar behaviour at the 6-methyl group.1-Aminophenazine fails to form a diazonium salt that will couple with -naphthol (though it will couple with phloroglucinol) because the phenazine-1-diazonium cation reacts rapidly with water and is oxidized to a 1-diazo-phenazinone that has weak coupling ability. 2-Amino-phenazine behaves similarly. ... 

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