Alkylation of acetylacetonate

Alkylation of acetylacetone chelates is generally unsuccessful, but carbon—methylene bonds can be formed by chloromethylation,279 reaction with ethyl diazoacetate,287 reaction with thioacetals288 (equations 64, 65 and 66) and by the Mannich reaction (Scheme 73).279 The Mannich base can be quatemized with methyl iodide and converted by cyanide ion into a cyanomethyl-substituted chelate. 

Pavolini (118) who prepared curcumin by condensation of acetylacetone with vanilline. He observed that Knoevenagel condensation, one of the main side reactions, could be suppressed by adding boric oxide. This method was further developed by Pabon (119) who first prepared a complex from acetylacetone and boric anhydride and reacted the product with vanilline in the presence of triisopropyl borate and butylamine. Yields calculated on vanilline were thus improved from 10% to 80%. Besides several other indutrial applications (120-123) the method was also used for the synthesis of dihydroyashabushiketol (6) (11) and the tetramethylether of oregonin (11) (14). By selective alkylation of acetylacetone at C-3 Pedersen and associates exploited the above method for the preparation of a series of non-natural diaiylheptanoids substituted at C-4 (124). 

Results from alkylation of acetylacetone enolates in dipolar aprotic solvents... 

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