Influence of the Double‐Bond Geometry of the Michael Acceptor on Copper‐Catalyzed Asymmetric Conjugate Addition

Abstract

Keywords: Michael addition / Asymmetric catalysis / Diethylzinc / Copper / Double-bond geometry Focusing on mechanistic aspects, a study of the influence of the (E)/(Z) double-bond geometry of the Michael acceptor on the enantioselectivity of copper-catalyzed asymmetric conjugate addition reactions has been realized. In spite of numerous articles concerning copper-catalyzed asymmetric conjugate addition reactions, the major factors of such a reaction are quite difficult to elucidate. Although our experiments have not allowed us to define strict rules, they have high-

Phosphoramidite: privilegierte Liganden in der asymmetrischen Katalyse

“…[190] Bemerkenswerterweise konnte durch Vor kurzem wurde die Wirkung der Doppelbindungsgeometrie des Michael-Akzeptors auf die Enantioselektivität eingehend untersucht. [191] Dabei stellte sich heraus, dass die Substituenten in der b-Position die Seitenselektivität des nucleophilen Angriffs über eine mögliche d-p*-Wechselwirkung mit dem Kupfer beeinflussen können (vgl. auch Abschnitt 4.1.2), allerdings wurde bisher keine eindeutige Tendenz beschrieben.…”

Gold(I)‐Catalysis for the Synthesis of Terpenoids: From Intramolecular Cascades to Intermolecular Cycloadditions

“…[132] 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 Our enantioselective total synthesis of nardoaristolone B (122) [139] started from 2-methyl-2-cyclohexenone (127) which was converted into 128 by the enantioselective conjugate addition in the presence of a chiral phosphoramidite ligand and trapping of the resulting enolate with methallyl iodide (Scheme 28). [140] Isomerization of exo-olefin of 128 with RhCl 3 ·xH 2 O provided ketone 124. 1,5-Enyne 125 was obtained via enol triflate 129 by Sonogashira cross-coupling.…”

Cu‐ and Ni‐Catalyzed Conjugated Additions of Organozincs and Organoaluminums to α,β‐Unsaturated Carbonyl Compounds

“…The relevant issues regarding various aspects of the reaction mechanism have been discussed in reviews by Alexakis [13] and Feringa [14]. Some aspects of the reaction mechanism, such as a precatalyst formation [21], the double bond geometry of the Michael acceptor [22], and the ''styrene effect'' [23] have also been discussed.…”