Carboxylic acids exhaustive methylation

Trimethylaluminum, which exhaustively methylates ketones (16-27), also exhaustively methylates carboxylic acids to give tert-butyl compounds (see also 10-99) ... 

Carboxy-6-hydroxythiazolo[2,3-/ [ 1,6]-naphthyridin-4-ium-3-carboxylate (152) (beminamycinic acid) underwent exhaustive methylation to afford methyl 8-methoxy-6-(l-methoxycarbonyl-2-methylthiovinyl)-5-oxo-5,6-dihydro-1,6-naphthyridine-2-carboxylate (153) (Mel, Ag20 low yield)293 or hydrogenolysis to furnish a separable mixture of 6-(l-carboxylatoethyl)-8-hydroxy-l,2,3,4-tetrahydro-l,6-naphthyridin-6-ium-2-carboxylic acid (154) and 8-hydroxy-1,2,3,4-tetrahydro-l,6-naphthyridine-2-carboxylic acid (155) (Raney Ni, NaOH, H20 unstated yields).274... 

Dimethoxy-8-vinylphenanthrene [xlvih] is the end-product of exhaustive methylation of apomorphine dimethyl ether. It can be oxidized to the 8-carboxylic acid [xlix] [64-65], which oan be converted via the amine to 3 4 8-trimethoxyphenanthreno [l] [66], identical with an authentic spcoimon [07] (see Chap. XXII). 

From ecgonine and its derivatives, by exhaustive methylation and reduction, three isomeric cycloheptatriene carboxylic acids, one cyclo-heptadienecarboxylic acid, three cycloheptenecarboxylic acids, and cyclo-heptanecarboxylic acid have been prepared (144). 

Trimethylaluminum exhaustively methylates tert. alcohols to alkanes, ketones to g m-dimethyl compds., and carboxylic acids to tert-butyl compds. - E Excess trimethylaluminum allowed to react... 

Friedel-Crafts cyclization of phenoxy ether 70 leads to the corresponding xanthone TJ Exhaustive oxidation of the methyl group leads to the carboxyl lie acid, xanoxate (72). ... 

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