Micheline Charpentier-Morize

Alkylation du trifluoroacetylacetate d'ethyle methode generale d'acces aux trifluoromethylcetones. 2ème Partie: alkylations indirects du TFAAE

Resume A versatile method of alkylation of ethyltrifluoroacetylacetate (ETFAA) allowed selective C-alkylation of ETFAA, whatever the structure of alkyl halide was, providing that the carbonyl function was masked into a dioxolan 3 or a N,N-dimethyl hydrazone 5 . These last derivatives were easily alkylated and their specific deprotection led to various C-alkylated ETFAA which in turn allowed, by a simple decarbethoxylation, the preparation of the corresponding trifluoromethyl ketones in good yields.

Methods generale d'acess aux trifluoromethylcetones. 1ère partie: Alkylation directe du trifluoroacetylacetate d'ethyle

Resume Alkylation of Ethyl 4,4,4 trifluoroacetylacetate (ETFAA) 1 by alkyl halides presented some typical features. The reaction was very slow and led preferentially to O-alkylated products. However, with activated halides and under some peculiar conditions, it was possible to obtain selectively C-alkylated products 3 and 4 in good yields.

Friedel-crafts reaction of α-chloroaldimines : possible intermediacy of α-imidoylcarbenium ions

Abstract α-Chloroaldimines are arylated at the α-position under Friedel-Crafts conditions via intermediacy of α-imidoylcarbenium ions.

Ions α-cétocarbenium : Influence de la nature de la fonction carbonyle sur la reactivite des ions α-ceto 4-t.Bu cyclohexylcarbenium

Abstract α-keto 4-t.Bu cyclohexylcarbenium ions formed by AgSbF 6 -CH 2 Cl 2 dehalogenation of α-keto 1-bromo 4-t.Bu cyclohexanes, give the corresponding α-ethylenic carbonyl compounds and bicyclic oxonium salts. The ratio of products does not vary according to the electronic environment of the carbonyl function but depends on the size of the adjacent group, suggesting that the α-ketocarbenium ion conformation determines the product ratio.

Alkylation of ethyl 4,4,4-trifluoroacetoacetate. First example of a reversible O-alkylation process leading to C-alkylation

In aprotic polar solvents the ratio of O vs. C alkylation products of ethyl 4,4,4-trifluoroacetoacetate (ETFAA)can be dependent on reaction time; in hexamethylphosphoric triamide (HMPA) or acetone, the SN2 cleavage of enol ethers of ETFAA with sodium iodide was observed with concomitant formation of the sodium enolate and the corresponding iodides, and in the case of an activated iodide the mono- and di-alkylation products resulted quantitatively.

Carbocationic cyclizations initiated by dehalogenation of unsaturated α-bromoimine

Abstract Electrophilic dehalogenation (AlCl 3 -CH 2 Cl 2 ) of the ω-olefinic α-bromo α 1 -phenyl imine 1 leads by two successive carbocationic cyclizations to the 5-9 methanobenzocyclooctene system