Methyl 2-methoxytetrafluoropropionate as a synthetic equivalent of methyl trifluoropyruvate in the Claisen condensation. The first synthesis of 2-(trifluoroacetyl)chromones and 5-aryl-2-hydroxy-2-(trifluoromethyl)furan-3(2H)-ones

Chromone: A Valid Scaffold in Medicinal Chemistry

“…Other modifications to the synthesis of chromones via Claisen condensation were also reported [237,240,241] . Essentially, the reported modifications were focused in finding mild reaction conditions, such as the employment of triethylamine as solvent and base [242] although the use of other catalysts like LiH [243] , NaH in THF [195] and NaH in pyridine [204,244,245] have also been described. Mozingo et al [246] reported the use of metallic cyclisation under acidic conditions [247] .…”

Synthesis of 5-aryl-2-hydroxy-2-(trifluoromethyl)furan-3(2H)-ones and their reactions with aromatic 1,2-diamines, hydrazine and hydroxylamine

“…To the best of our knowledge, little is known about the Claisen-type preparation of 1,3-diketones from methyl 2-methoxytetrafluoropropionate and their deprotection to trifluoromethylated 1,2,4-triketones, which we deemed suitable for the synthesis of more complex CF 3 -containing molecules. Indeed, apart from two our communications, 5,8 there is only one report, in which this ester was used as a carbonyl component in the condensation with cyclohexanone without deprotection. 11 We found that methyl 2-methoxytetrafluoropropionate reacted with acetophenone and p-chloroacetophenone under Claisen reaction conditions (refluxing ethanol and NaOEt as a base) affording, after hydrochloric acid hydrolysis, 1,3-diketones 6a,b in high yield (73e79%).…”

A Convenient Approach to CF3‐Containing N‐Heterocycles Based on 2‐Methoxy‐2‐methyl‐5‐(trifluoromethyl)furan‐3(2H)‐one

“…Indeed, the intramolecular cyclization of intermediate B through a nucleophilic attack of the NH 2 group of the hydrazone moiety at a more electrophilic carbonyl group appears to be the preferred pathway (path a ). In addition, the formation of any by‐products, such as pyridazinone D (path b ),10,13 has not been observed.…”

“…From this point of view furan‐3(2 H )‐one ( 11 ) can be considered as a cyclic acetal of the corresponding 1‐(trifluoromethyl)‐substituted 1,3,4‐triketone 12 (Figure 3). Furthermore, this investigation has to expand undoubtedly our knowledge concerning the chemistry of trifluoromethyl‐containing furan‐3(2 H )‐ones 10,11…”