99285-86-6Relevant academic research and scientific papers
Stereospecificite de l'addition de Michael d'enethiolates avec les enones acyliques
Kpegba, Kafui,Metzner, Patrick,Rakotonirina, Rose
, p. 2041 - 2056 (2007/10/02)
1,4-Addition reaction of lithiated dithioesters with acyclic β-substituted E enones affords diastereomeric 5-oxo-alkanedithioates.Anti configuration was assigned to yhe major diastereoisomer by chemical correlation.This stereochemistry depends on the configuration of the prochiral partners.The cis/trans ratio of intermediate enethiolates was analyzed by trapping experiments.Two cases of highly selective cis deprotonation of dithioesters were observed.Michael addition with E-enones (3-penten-2-one, chalcone) occurs with high stereospecificity : anti/syn product ratios are identical to the cis/trans enethiolate ratios.A pseudo-cyclic transition state is proposed with substituents of the enone C-C double bond occupying favorable equatorial positions.The 1,4-addition reaction is kineticaly controlled.In contrast to ester enolates, enethiolates allow the use of enones without the need of tertiobutyl or phenyl groups.The observed diastereoselectivity (ratio anti/syn up to 95:5) offers a new means of creation of two vicinal carbon substituted asymmetric centers by carbon-carbon bond formation in the acyclic series.Poor selectivities were however observed when using unsaturated diesters as acceptors.
Stereoselective Enolization of Methyl Dithiopropanoate by Adsorption on Alumina-Potassium Fluoride
Villemin, Didier
, p. 870 (2007/10/02)
Alkylation of methyl dithiopropanoate with benzyl chloride at room temperature by adsorption on alumina-potassium fluoride is more selective than in solution under selected conditions (Pri2NLi; -70 deg C).
