5Addition to R S M L Nu d.e.% H Me Et Ph MeMgI EtMgBr PhMgBr EtMgI PhMgI334350>60667583Cram & Elhafez, J Amer Chem Soc 1952, 74, 5828.
6Faulty Assumptions Ground state and reactive conformation are wrong. Ground state and reactive conformation (TS) cannot be assumed to be the same.The directing influence of substituents does not only derive from their steric effects. Electronic interactions are crucial.The C=O group assumes pyramidal state early, therefore Cram model is unfavourable.
15Auxiliary attached to nucleophile J C S Perkin I 1981, 1278
16Organometallic: Chiral ligand Tetrah Lett 1986, 27, 5711
17Allylic nucleophiles Alternative route to aldol-type products Two new chiral centres introducedComplication: reaction at C-1Achiral reactants: syn and anti racematesChiral reactants: in principle one major stereoisomer
31Chiral ligand as catalyst Organometallic reagent must be relatively unreactive towards C=O unless combined with the catalyst – ligand acceleration.Catalyst must have suitable 3D structure to provide high e.e.
32Dialkylzinc addition to aldehydes R Nu e.e., %Ph MePh EtPh Bup-Cl-Ph Etp-MeO-Ph Et2-Furyl C5H >95(E)-C6H5-CH=CH Et(E)-Bu3SnCH=CH C5HPhCH2CH2 EtJ Amer Chem Soc 1986, 108, 6071