SELECTIVE REACTIONS OF THIOLATE ANIONS WITH 4-HYDROXY-<i>E</i>-2-ALKENOIC ESTERS OR 4-METHANESULFONYLOXY-<i>E</i>-2-ALKENOIC ESTERS. SYNTHESIS OF 2-ALKEN-4-OLIDES (Δ<sup>α,β</sup>-BUTENOLIDES) AND<i>E</i>,<i>E</i>-2,4-ALKADIENOIC ESTERS
Methyl 4-hydroxy-E-2-alkenoates prepared from aldehydes in one step, undergo the Michael reactions with thiolate anions to give 4-alkanolide derivatives, which are converted into 2-alken-4-olides. Methyl 4-methanesulfonyloxy-E-2-alkenoates undergo the substitution reactions, and subsequent treatments give methyl E,E-2,4-alkadienoates.
Catalytic conversion of (β,γ-unsaturated esters, amides and nitriles into γ-alkoxy or γ-hydroxy α,β-unsaturated derivatives induced by persulfate anion oxidation of diphenyl diselenide
The reaction of β,γ-unsaturated esters, amides and nitriles with catalytic amounts of diphenyl diselenide and an excess of ammonium persulfate in alcohols or in water affords γ-alkoxy or γ-hydroxy α,β- unsaturated derivatives, respectively, in good yields.
Palladium(0)-catalysed reactions of 4-chloroacetoxyalk-2-enoicesters with amines selectively give 4-aminoalk-2-enoic esters, which are readily converted into pyrrol-2(5H)-ones (4-but-2-enelactams).
Regioselectivity in the ene reaction of singlet oxygen with alkenes bearing an electron withdrawing group at β- position
作者:Manolis Stratakis、Michael Orfanopoulos
DOI:10.1016/s0040-4039(96)02469-0
日期:1997.2
Electronic repulsions between a perepoxide intermediate and the allylic functionality in the product forming transition state, direct the regioselectivity in the photooxygenation of trisubstituted alkenes bearing an electron withdrawing group at β- position.
High 1,2-Asymmetric Induction in Radical Reactions: Radical Addition to<i>γ</i>-Hydroxy<i>α</i>,<i>β</i>-Unsaturated Carboxylic Esters and Sulfones
作者:Katsuyuki Ogura、Akio Kayano、Motohiro Akazome
DOI:10.1246/bcsj.70.3091
日期:1997.12
High 1,2-asymmetric induction was realized by the addition of a 1-hydroxy-1-methylethyl radical to conformationally flexible (E)-γ-hydroxy α,β-unsaturated carboxylic esters and sulfones (1 and 2, respectively). Upon the irradiation (> 290 nm) of (E)-1 and benzophenone in 2-propanol, the 1-hydroxy-1-methylethyl radical was generated in situ and added to (E)-1 with high anti-stereoselectivity. The bulkier