Reactions of pentafluorobenzoylpyruvic ester and its copper(II) chelate with dinucleophiles

(Het)aroylpyruvic acids and their derivatives as promising building blocks for organic synthesis

“…30 It is noteworthy that the reaction of pentafluorobenzoylpyruvate 31a with 1,2-diaminoethane gives, depending on the conditions, either 3-pentafluorobenzoyl-(84a) or 3-(2-hydroxy-3,4,5,6-tetrafluoro)benzoyl-methylidenepiperazin-2-ones (84b). 3,5 The piperazinone 84a is formed when the pyruvate 31a is treated with a large excess of ethylenediamine at 20 8C in a MeOH ± AcOH mixture, and the product 84b is produced on refluxing equimolar amounts of the reactants in methanol. Non-symmetric 1-methyl-and 1-phenyl-1,2-diaminoethanes have been shown 142 to react selectively with the APA esters 2 on refluxing in an ethanol ± acetic acid mixture to give the corresponding 6-methyl-or 6-phenyl-3-aroylmethylenepiperazin-2-one 85 as the only reaction product.…”

“…1, 2, 11 ± 23 Pentafluorobenzoylpyruvates are prepared from pentafluoroacetophenone in the presence of lithium hydride. 3,5,24,25 It is convenient to isolate and purify labile AP as their copper(II) chelates 3. 1,13,14,16 This is especially required in the case of pentafluorobenzoylpyruvates, 5,24,25 which cyclise very easily to chromone derivatives due to the presence of ortho-fluorine atoms in the benzoyl substituent.…”

“…3,5,24,25 It is convenient to isolate and purify labile AP as their copper(II) chelates 3. 1,13,14,16 This is especially required in the case of pentafluorobenzoylpyruvates, 5,24,25 which cyclise very easily to chromone derivatives due to the presence of ortho-fluorine atoms in the benzoyl substituent. Hydrolysis of the esters 2 to the corresponding acids 4 is normally carried out in an acid medium, 1,23,26,27 although examples of alkaline hydrolysis are also documented.…”

“…aroylpyruvic acids and their derivatives as promising building blocks for organic synthesis in alcohol, while the product mixture is produced when the reactants are refluxed 3,5,176. 4(5)-Monosubstituted 2-aminophenols and 1-amino-2-naphthol react with the AP 2 similarly to 2-aminophenol yielding 6(7)-derivatives of 3-aroylmethylidene-3,4-dihydro-1,4-benzoxazin-2(2H)-ones 134a ± d and 3-benzoylmethylidene-3,4-dihydronaphtho[2,1-b]-1,4-benzoxazin-2(2H)-one(135), respectively 145,175,177.…”