91585-47-6Relevant academic research and scientific papers
Reactions of Enolates with Vinyl Selenoxides and Vinyl Selenones. One-Step Synthesis of Cyclopropylcarbonyl Compounds
Ando, Ryoichi,Sugawara, Tomoo,Shimizu, Makoto,Kuwajima, Isao
, p. 2897 - 2904 (2007/10/02)
In the reactions with enolate anions, organoselenium moieties of aryl vinyl selenoxides and selenones have exhibited two important roles, e.g., activation of C=C bonds for conjugate addition reaction and behaviors as excellent leaving groups.Owing to such characteristic fetaures, ketone enolates react with p-chlorophenyl vinyl selenoxide to afford the corresponding cyclopropyl ketones through an initial conjugate addition followed by substitution processes.On the other hand, use of vinyl selenones usually gives much better results with anionic species of active methylene compounds.Vinyl selenones bearing hydroxyl, ketone, and ester groups can also be employed equally well for this type of transformation.
Vinyl Selenides and Selenoxides: Preparation, Conversion to Lithium Reagents, Diels-Alder Reactivity, and Some Comparisons with Sulfur Analogues
Reich, Hans J.,Willis, William W.,Clark, Peter D.
, p. 2775 - 2784 (2007/10/02)
A variety of aryl vinyl selenides are prepared by reaction of vinyl Grignard reagents with aryl selenyl bromides or by reductive elimination of the adducts of lithiums with carbonyl compounds.Deprotonation of phenyl vinyl selenide is achieved with LDA at -78 deg C in THF.Vinyl selenides with β-alkyl groups require LiTMP and warmer temperatures (-50 deg C) for complete deprotonation.Allylic lithium reagents were obtained from 1-propenyl and 2-methyl-1-propenyl selenides whereas 1-butenyl or 3-methyl-1-butenyl selenides gave vinyl lithium reagents.Reaction with electrophiles proceeds in good to excellent yield.Primary halides require HMPA to react well.Unhindered carbonyl compounds react without enolization.Deprotonation with LDA is shown to be reversible, and during competitive deprotonation studies with LDA, aryl vinyl sulfides are found to be thermodynamically less acidic than aryl vinyl selenides (KS/Se=0.21 for phenyl vinyl and 0.3 for m-(trifluoromethyl)phenyl vinyl).Deprotonation with LiTMP is shown to be irreversible, and competitive deprotonation studies showed vinyl selenide to be kinetically more acidic as well S/Se=0.37 (phenyl vinyl),0.42 (m-(trifluoromethyl)phenyl vinyl)>.Most studies have shown sulfur compounds to be more acidic. m-(Trifluoromethyl)phenyl allyl sulfide as expected, is more acidic than selenium compound (kS/Se=3.8).Vinyl selenoxides can be prepared with m-chloroperbenzoic acid.They are not thermally stable enough to serve as acetylene equivalents in Diels-Alder reactions.Phenyl vinyl selenide gives a Diels-Alder addition product with 1,4-diphenylisobenzofuran but failed to give cycloaddition products with less reactive dienes.Phenyl vinyl selenoxide does not give a useful yield of lithium reagent upon reaction with amide bases.
