Anne-Marie Frisque-Hesbain

1-aza-1,3-dienes - Diels-alder Reactions With Alpha,Beta-unsaturated Hydrazones

The Alpha, Beta unsaturated hydrazone reacts regioselectivity with a wide range of dienophiles to give the corresponding [4+2] adducts. Reductive cleavage of the N N bond in the adducts gives tetrahydropyridines.

Synthesis of Alkyl-halides Under Neutral Conditions

Abstract Primary and secondary alcohols are efficiently converted to the corresponding alkyl halides under neutral conditions.

2-aza-1,3-dienes: Methods of synthesis and stereochemical studies

2-Aza-1,3-dienes bearing an activating trialkylsilyloxy group at C-3 have been prepared via three routes. The first route involves the silylation of N-acylimidates which are readily available from iminoether hydrochlorides and acid chlorides. According to a more general route towards these doubly activated dienes, N-trialkylsilylimidates and N-trialkylsilylimines derived from non-enolizable aldehydes were conveniently converted in a one-pot sequence into the corresponding azadienes by reaction with an acid chloride in the presence of triethylamine. Finally, cyclic dienes could be prepared by direct silylation of glutarimide on both oxygens with trialkylsilyltriflate in the presence of triethylamine. The configuration and conformation of 2-azadienes have been established by H-1, C-13 and N-15 NMR spectroscopy.

Nonstereospecificity in the Cyclo-additions of Keteneiminium Salts To Olefins - Evidence for a Stepwise Mechanism

The stereospecificity of the olefin-keteneiminium salt reaction is shown to be dependent on the nitrogen substituents. This is taken as evidence for a stepwise mechanism.

Synthesis of acyl halides under very mild conditions

On treatment with tetramethyl-α-halogenoenamines at room temperature or below, carboxylic acids are converted into acyl halides in high yields under neutral conditions.

Heterocyclization of 3-trifluoroacetyllactams By Hydrazines

3-Trifluoroacetyllactams may heterocyclize with hydrazine or with its methyl or phenyl derivative either without ring opening to annelated trifluoromethylpyrazoles or by Ring Opening - Ring Closure (RORC) reaction to zwitterionic salts of 4-omega-alkylamino-5-hydroxy-3-trifluoromethylpyrazoles.

Vicinal Alkylation of Olefins, Regioselective and Stereoselective Addition of [cm + Cn] Units To Cyclopentadiene

Adducts of alkyl(phenylthio)ketenes to cyclopentadiene are cleaved with KOH-t-BuOK with retention of configuration at three centers. This observation broadens the synthetic potential of the method of vicinal alkylation of olefins. This method has been used for the vicinal addition of [Cm + Cn] units to cyclopentadiene.