Huguette Molines

Synthesis of 1,1,1 - trifluoro-2-penten-4-one

Abstract The 1,1,1-trifluoro-2-penten-4-one has been prepared from trifluoroacetaldehyde by two different ways. Its condensation with a cyclohexanone enamine leads, by annelation, to 4-trifluoromethyl-Δ-1,9 (and Δ-9,10)-octalin- 2-one.

A convenient synthesis of ethyl 3,3,3,-trifluoropropanoate and its 2-bromo derivative

Abstract Ethyl 3,3,3-trifluoropropanoate and ethyl 2-bromo-3,3,3-trifluoropropanoate have been synthesized. A common intermediate ethyl 3-chloro (or 3-bromo)-3,3-difluoropropanoate is involved in the two syntheses. These esters are obtained by oxidation of the corresponding acetals resulting from the radical addition of CF 2 BrCl or CF 2 Br 2 to ethyl vinyl ether.

Synthesis of ethyl 3-fluoroacrylate from a Tarrant–Stump acetal

Abstract Diethyl ketal of 3,3-dibromo-3-fluoropropanal was prepared by UV-initiated condensation of fluorotribromomethane with ethyl vinyl ether, following Tarrant–Stump procedure. Direct oxidation of this acetal to ethyl 3,3-dibromo-3-fluoropropanoate was carried out using Caro’s acid. On treating this ester with triethylamine, dehydrobromination took place, yielding ethyl 3-bromo-3-fluoroacrylate. Finally, a selective reduction of the bromine atom by tributyltin hydride led to ethyl 3-fluoroacrylate.

1-Bromo-3-trifluoromethylbut-2-ene: synthesis and electrophilic reactivity

Abstract A three-step synthesis of 1-bromo-3-trifluoromethylbut-2-ene in 54% overall yield isreported starting from 1,1,1-trifluoroacetone. The electrophilic reactivity of this compoundtowards various nucleophiles has been studied. Thus, for example, condensation withthe sodium salt of diethyl malonate gave ethyl 2-carboethoxy-5-trifluoromethylhex-4-enoate in 66% yield.

Thermolysis of the Chlorofluorocarbene 1-Ethoxy-1-Phenoxyethylene Adduct to Phenyl 2-Fluoroacrylate

Abstract The preparation of 1-ethoxy-1-phenoxyethylene 1 is described. Its condensation with chlorofluorocarbene gives 2,2-chlorofluorocyclopropanone acetal 2, thermolysis of which leads to phenyl 2-fluoroacrylate 3.

Synthesis of cis and trans β-fluoroacrylic acid esters

Abstract Cis and trans β-fluoroacrylic acid esters 1 are versatile fluorinating building blocks. Their synthesis in 5 steps (57% overall yield), Starting from tribromofluoromethane and ethyl vinyl ether, is described. This convenient method affords a mixture of cis (new compound) and trans [1] isomers in a 70:30 ratio. Their separation was performed by efficient distillation.

1-BROMO-4,4,4-TRIFLUORO-3-(TRIFLUOROMETHYL)BUT-2-ENE : SYNTHESIS AND ELECTROPHILIC REACTIVITY

Abstract A two-step synthesis of 1-bromo-4,4,4-trifluoro-3-(trifluoromethyl)but-2-ene in 35% overall yield is reported starting from commercially available hexafluoroacetone. The electrophilic reactivity of this new compound towards various nucleophilic reagents has been studied. Substitution products or ones arising from allylic rearrangement are obtained depending on the nature of the nucleophile.

Synthesis of (±)-cis-6-methyltetrahydropyran-2-ylacetic acid, a natural product from Viverra civetta, using organoselenium-mediated cyclisation reactions

Two highly stereoselective syntheses of the natural product (±)-cis-6-methyltetrahydropyran-2-ylacetic acid (1) are described. The shorter of these is a three-step synthesis involving kinetic alkylation of the dianion derived from benzyl acetoacetate with 4-bromobut-1-ene, followed by organoselenium mediated cyclisation with N-phenylselenophthalimide, to give benzyl 6-phenylselenomethyl-5,6-dihydro-4H-pyran-2-ylacetate (11) and benzyl 6-phenylselenomethyltetrahydropyran-2-ylideneacettate (12), which upon reaction with Raney nickel under 100 atm of hydrogen directly affords compound (1).

Preparation of 1-Aryl-4-(trifluoromethyl)penta-1,3-dienes by Wittig-Horner Condensation

Abstract A direct route to 1-aryl-4-(trifluoromethyl)penta-1,3-dienes is described using the Wittig-Horner reaction of diethyl (3-(trifluoromethyl)-but-2-enyl)phosphonate anion with aromatic aldehydes or trifluoroaceto-phenone.

Regioselective nucleophilic additon-elimination to β,β-bis(trifluoromethyl) acrylic esters

Abstract Reaction of β,β-bis(trifluoromethyl)acrylic esters 1 with nucleophilic reagents in aprotic media has been studied. A regioselective addition-elimination is observed leading to compounds 3 (ethyl α substituted 3-trifluoromethyl-4,4-difluorobut-3-enoate). The second CF 3 dramatically changes the reactivity of the acrylic ester as there is no classical Michael addition as for β-trifluoromethylacrylic ester [1]. In the case of amines, a mixture of 3 and saturated products 4 is obtained. Traces of 4 are also formed with anionic reagents. So, regioselective formation of carbanion 2 followed by a fluoride ion elimination is postulated.