Dialkylzinc reagents, addition with carbonyls

Oguni has reported asymmetric amplification [12] ((-i-)-NLE) in an asymmetric carbonyl addition reaction of dialkylzinc reagents catalyzed by chiral ami-noalcohols such as l-piperidino-3,3-dimethyl-2-butanol (PDB) (Eq. (7.1)) [13]. Noyori et al. have reported a highly efficient aminoalcohol catalyst, 2S)-3-exo-(dimethylamino)isobomeol (DAIB) [14] and a beautiful investigation of asymmetric amplification in view of the stability and lower catalytic activity of the het-ero-chiral dimer of the zinc aminoalcohol catalyst than the homo-chiral dimer (Fig. 7-5). We have reported a positive non-linear effect in a carbonyl-ene reaction [15] with glyoxylate catalyzed by binaphthol (binol)-derived chiral titanium complex (Eq. (7.2)) [10]. Bolm has also reported (-i-)-NLE in the 1,4-addition reaction of dialkylzinc by the catalysis of nickel complex with pyridyl alcohols [16]. 

Soai ei al. reported the catalytic asymmetric automultiplication in the addition of the dialkylzinc reagents to pyrimidine aldehydes without decrease in the optical purity of the product. The 1,2-addition in the presence of a small amount of optically active material resulted in enhancement of the ee value in the product formation. ) The asymmetric reaction was widely spread to the use of chiral crystals as a chiral trigger. The reaction promoted on the surface of the crystal of quartz gave optically active carbonyl addition product in 97% ee. Furthermore, the reaction with chiral crystals of NaClOs, benzoylglycine, and cocrystals resulted in the formation of product with high ee value. 

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