| Abstract
| - Samarium(II) iodide has been employed to promote a tandemintermolecular carbonyl addition/intramolecular nucleophilic acyl substitution sequence, generatingseven- through nine-memberedmonocyclic, bicyclic, and tricyclic ring systems with good yields andhigh diastereoselectivities.This tandem reaction consists of an intermolecular reactionfollowed by an intramolecular ringexpansion that results in a formal [m + n]cycloaddition, starting from extremely simple, readilyavailable substrates. The regioselectivity and stereoselectivityof the process arise from a tuningof the reducing power of samarium(II) iodide with nickel(II) iodide inthe first step and irradiationwith visible light in the second. By using this method, a varietyof structural motifs have beenassembled rapidly in good yields.
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