Fluorine-containing Imines

Acylimines of hexafluoroacetone and methyl trifluoropyruvate in cyclocondensation with 2-aminopyridines

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Cyclocondensation of acylimines of hexafluoroacetone and methyl trifluoropyruvate with 2 aminopyridines afforded earlier unknown fluoro containing 2H pyrido[1,2 a] [1,3,5]triazines.It is known that acylimines of hexafluoroacetone (HFA) and methyl trifluoropyruvate (MTFP) in cyclo condensation with bisnucleophiles act as 1,3 and 1,2 bis electrophilic reagents 1,2 and serve as promising starting material for the synthesis of various fluoro containing heterocycles. For instance, dehydration of adducts of HFA perfluoroacylimines and perfluorocarboxamides with oleum gives 1,3,5 oxadiazines; 3 reactions of HFA and MTFP benzoylimines with 6 aminouracil give 4 pyrimido and pyrrolopyrimidines, respectively; dehydration of the adduct of HFA ethoxycarbonylimine and 2 aminopyrimi dine with PCl 5 gives pyridotriazine.

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“…Cyclocondensation of acylimines of hexafluoroacetone and methyl trifluoropyruvate with 2 aminopyridines afforded earlier unknown fluoro containing 2H pyrido[1,2 a] [1,3,5]triazines.…”

“…For instance, dehydration of adducts of HFA perfluoroacylimines and perfluorocarboxamides with oleum gives 1,3,5 oxadiazines; 3 reactions of HFA and MTFP benzoylimines with 6 aminouracil give 4 pyrimido and pyrrolopyrimidines, respectively; dehydration of the adduct of HFA ethoxycarbonylimine and 2 aminopyrimi dine with PCl 5 gives pyridotriazine. 5 In the present work, we studied the cyclocondensation of HFA and MTFP acylimines with 2 aminopyridines, which yields earlier unknown fluoro containing 2H pyrido [1,2 a] [1,3,5]tri azines. The compounds obtained can be regarded as po tential biologically active substances.…”

“…Pyridotriazines are known to exhibit high fungicidal, 6 antimitotic, 7 and cyto static activities. 8, 9 The transformations studied follow a two step scheme: (1) addition of 2 aminopyridine to the C=N bond of imines 1 and 2 to give adducts 4 and 5 and (2) dehyd ration of adducts 4 and 5 with PCl 5 to 2H pyri do[1,2 a] [1,3,5]triazines 6 and 7. In the case of 2 amino 4 methylpyridine (3a), intermediate adducts 4a and 5a (Scheme 1) were isolated in the individual state and char acterized.…”

“…The cyclocondensation of 2 aminopyridines 3b-f with acylimines of HFA (1b-f) and MTFP (2b-e) (equimolar amounts of the reagents were mixed in ben zene at 20 °C; after the exothermic reaction was com pleted, PCl 5 was added and the reaction mixture was refluxed until the precipitate dissolved; intermediate ad ducts were not isolated) afforded 2,2 bis(trifluoromethyl) 2H pyrido[1,2 a][1,3,5]triazines 6b-h and methyl 2 tri fluoromethyl 2H pyrido[1,2 a] [1,3,5]triazine 2 carboxy lates 7b-f in 55 to 74% yields (Scheme 2).…”