Nucleophilic addition of organolithium reagents

In contrast to the extraordinarily high preference for endo attack observed with camphor (1), nucleophilic additions of organolithium and Grignard reagents to norcamphor (3) proceed with exclusive attack of the nucleophile from the exo face of the carbonyl group. 

Such nucleophilic additions of organolithiums to olefins are of limited use in laboratories. Nevertheless, there are certain categories of alkenes and alkynes that undergo ready addition [15]. A secondary organolithium reagent is easily transformed to the more stable primary reagent via the rapid equilibration [16]. 

The reactions of bis(diethylamino)carbenium salt 113 are summarized in Scheme 28 [65]. Nucleophilic additions of Grignard reagents, organolithium reagents, enolates, amides, thiolates, and phosphite take place regioselectively... 

The chromium complex 46 of benzaldehyde imine is also a good substrate for asymmetric conjugate addition of organolithium reagents, where the reaction was mediated by a stoichiometric amount of chiral diether 18 in toluene to give, following propargylic electrophile incorporation, the cyclohexadienal 48 in up to 93% ee (Scheme 13) [38]. SAMP [(S)-l-amino-2-(methoxymethyl)pyrrolid-ine] hydrazones were used effectively in diastereoselective nucleophilic additions to (arene)Cr(CO)3 complexes [39]. 

Addition of Grignard reagents and organolithium compounds to the pyridazine ring proceeds as a nucleophilic attack at one of the electron-deficient positions to give initially... 

---