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ring closure reactions ring closure reactions O 0130 -065First Example of Samarium Diiodide-Promoted Sequential Cyclization and Ring-Expansion Reactions of α-Bromomethyl Cyclic β-Keto Esters to Homologated γ-Keto Esters.-Reduction of cyclic bromomethyl esters such as (I) or (VI) results in ring-expansion to homologated γ-keto esters (II) and (VIII). This method can be complementary to traditional free-radical methods. -(HASEGAWA, E.; KITAZUME, T.; SUZUKI, K.; TOSAKA, E.; Tetrahedron Lett. 39 (1998) 23, 4059-4062; Dep. Chem., Fac. Sci., Niigata Univ., Ikarashi, Niigata 950-21, Japan; EN)