138852-01-4Relevant academic research and scientific papers
Michael addition of stannyl ketone enolate to α,β-unsaturated esters catalyzed by tetrabutylammonium bromide and an ab initio theoretical study of the reaction course
Yasuda, Makoto,Chiba, Kouji,Ohigashi, Noriyuki,Katoh, Yasuhiro,Baba, Akio
, p. 7291 - 7300 (2007/10/03)
Michael addition of stannyl ketone enolates to α,β-unsaturated esters was accomplished in the presence of a catalytic amount of tetrabutylammonium bromide (Bu4NBr). Other typical systems using lithium enolate or silyl enolate with catalysts (TiCl4 or Bu4NF) failed to give the desired products. The bromide anion from Bu4NBr coordinates to the tin center in enolate to accelerate the conjugate addition where a five-coordinated tin species was generated. The coordination of the bromide anion significantly raises the HOMO level of tin enolate and enhances its nucleophilicity. The conjugate addition provides the intermediate Michael adduct, which has an ester enolate moiety, and the adduct immediately transforms to α-stannyl γ-ketoester by keto - enol tautomerization. This step contributes to the stabilization of the product system and leads to a thermodynamically favorable reaction course. An ab initio calculation reveals that the activation energy in the reaction using the bromide anion is lower than that of the reaction without using it. The transition state in either reaction course has a linear structure, not a cyclic one. This system can be applied to a variety of tin enolates and α,β-unsaturated carbonyls involving enoates, enones, and unsaturated amides.
Stereoselective Synthesis of Trifluoromethylated Compounds with Controlled Adjacent Tertiary Carbons by Michael Addition to (E)-3-(Trifluoromethyl)acrylates
Shinohara, Noriyasu,Haga, Jiro,Yamazaki, Takashi,Kitazume, Tomoya,Nakamura, Shinichiro
, p. 4363 - 4374 (2007/10/02)
Michael addition reaction of various lithium enolates to ethyl (E)-3-(trifluoromethyl)acrylate (E)-1 was found to be one of the most effective routes to construct materials not only with a CF3 group but also readily distinguishable multiple functionalitie
Highly Diastereoselective Michael Addition Reactions of Lithium Enolates to Ethyl 3-Trifluoromethylacrylate
Yamazaki, Takashi,Haga, Jiro,Kitazume, Tomoya,Nakamura, Shinichiro
, p. 2171 - 2174 (2007/10/02)
Michael addition reactions of lithium enolates derived from ketones, esters, and amides to ethyl 3-trifluoromethylacrylate were found to proceed smoothly in moderate to excellent chemical yields as well as with a high degree of diastereoselectivity at the
