A new strategy for the preparation of an active Mn(0) and its use for radical cyclization reactions

Article abstract of DOI:10.1016/S0040-4020(98)01205-8

Reduction of Li₂-MnCl₄ with magnesium in THF afforded a fairly active manganese species which readily initiated radical cyclization of 2- iodoethanal allylic acetals at room temperature. The corresponding 2- bromoethanal acetals also provided the same cyclized products upon treatment with the activated manganese reagent at reflux in THF. This reagent can also be used to induce tandem radical cyclizations, and the 5-exo/6-endo and 5- exo/6-exo modes are both available to give the products with trans- stereochemistry with regard to ring-junction. Further, the intramolecular type of sequential generation and utilization of radical and anionic species with this reagent have also been studied.