FORMATION OF A SUBSTITUTED TETRAHYDROFURAN BY FORMAL [2-ATOM WITH 2 OLEFINS AT A NICKEL CENTER(2+1] COUPLING OF AN OXYGEN)

Formation of the tetrasubstituted tetrahydrofuran [9.2,1,1.(5,8)0.(2,1 0)0(4,9)]-pentadeca-6,12-diene (5) has been accomplished by the coupli ng of an oxygen atom (from nitrous oxide) with two olefins (norbornadi ene) at a Ni center. The reaction proceeds via a nickelacyclopentane c omplex: (2) that is subsequently oxidized by N2O to give an isolable o xa-nickelacyclohexane (3). Oxidation of 3 with iodine results in forma tion of the C-O bond of 5 (47% isolated yield) via C,O-reductive elimi nation.