Lanthanides Henry reaction

Jenner investigated the kinetic pressure effect on some specific Michael and Henry reactions and found that the observed activation volumes of the Michael reaction between nitromethane and methyl vinyl ketone are largely dependent on the magnitude of the electrostriction effect, which is highest in the lanthanide-catalyzed reaction and lowest in the base-catalyzed version. In the latter case, the reverse reaction is insensitive to pressure.52 Recently, Kobayashi and co-workers reported a highly efficient Lewis-acid-catalyzed asymmetric Michael addition in water.53 A variety of unsaturated carbonyl derivatives gave selective Michael additions with a-nitrocycloalkanones in water, at room temperature without any added catalyst or in a very dilute aqueous solution of potassium carbonate (Eq. 10.24).54... 

Strongly chelating ligands provide a sterically rigid ligand frame, a prerequisite for induction of asymmetry at the lanthanide center. Complexes derived from (S)-( — )-BINOL were thoroughly studied in the nitroaldol reaction (Henry reaction, Scheme 27) [250]. 

The basic character of lanthanide alkoxides such as Lu3(Of-Bu)9 seem to effect aldol, cyanosilylation, aldol, and Michael reactions [111]. Complexes 2 and 22, abbreviated as LnMB (Ln = lanthanide, M = alkali metal, B = BR IOL) [112] were thoroughly studied in the catalytic, asymmetric nitroaldol reaction (Henry reaction eq. (10)) [113]. 

One of the more reactive and selective catalysts of this type involves a bifunctional catalyst containing an alkali metal cation and an anionic lanthanide complex resulting from addition of excess binolate with lanthanide halides. Such catalysts have been used in asymmetric nitroaidol (Henry) reactions of ketones. Heterobimetallic Li-La alkoxo complexes (Figure 4.15) catalyzed these reactions with particularly high enantioselectivity. ... 

The lanthanide-alkali metal heterobimetallic complexes have also been shown to promote other reactions, such as nitro-Mannich (aza-Henry) reaction [154],... 

The first catalytic asymmetric aza-Henry reaction appears to have been reported by Shibasaki in 1999, as part of a general research program focused on heterobimetallic lanthanide complexes and their application in asymmetric catalysis [190]. In the event, a 1 1 3 mixture of KOt-Bu, Yb(Oi-Pr)3, and (i )-BINOL afforded an active catalyst suggested to have the structure 302 (Equation 32) [191]. This catalyst was shown to promote enantioselective additions of nitromethane to N-phosphinoylarylimines, including 300, to provide the corresponding products, such as 303, in 79 % yield and 91 % ee. 

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