Polar-Radical Cyclization Cascades with Magnesiated Nitriles

Naphthalene converts magnesiated ω-alkenylnitriles into bi- and tricyclic ketones via a polar-radical addition–cyclization cascade. One-electron oxidation of magnesiated nitriles generates nitrile-stabilized radicals that cyclize onto a pendant olefin and then rebound onto the nitrile through a reduction–cyclization sequence; subsequent hydrolysis affords a diverse array of bicyclo[3.2.0]­heptan-6-ones. Combining the polar-radical cascade with a 1,2:1,4-carbonyl-conjugate addition generates complex cyclobutanones containing four new carbon–carbon bonds and four chiral centers in one synthetic operation.