Subtle factors are important: radical formation and transmetallation in reactions of butyl cuprates with cyclohexyl iodide.

The reactions of Bu(2)CuLi[middle dot]LiI and Bu(2)CuLi.LiCN with cyclohexyl iodide are critically dependent upon subtle factors such as the surface properties of the reaction vessel, nature of the solvent still and lot of 'ultrapure' copper salt in addition to major effects such as the Li counterion.

Rapid-injection NMR study of iodo- and cyano-Gilman reagents with 2-cyclohexenone: observation of pi-complexes and their rates of formation.

Rapid-injection is a very useful technique for the preparation of temperature-sensitive and air-sensitive compounds in the cold, nitrogen-filled probe of an NMR spectrometer. We have used this method to prepare solutions of pi-complexes from 2-cyclohexenone and prototypical cuprates Me2CuLi.LiI and Me2CuLi.LiCN, and we have assigned structures on the basis of 1H and 13C NMR. In each case two pi-complexes were observed, and in the former, their rates of formation were measured by rapid-injection 1H NMR and EXSY spectroscopy. These results provide insights into the normal and anomalous conjugate addition reactions of organocuprates.