Samarium 6-endo cyclization

Thus, this method takes advantage of a relatively rapid 9-endo-trig cyclization, rather than undergoing other possible reactions with samarium iodide [32],... 

Curran, D. P. Synthesis of substituted cyclooctanols by a samarium(ll) iodide promoted 8-endo radical cyclization process. On the stereoselectivity of radical 4-exo-trig-cyclization of optically active ethyl (2E)-6-oxohex-2-enoates with samarium(ll) iodide. Chemtracts Org. Chem. 1994, 7, 351-354. 

Samarium diiodide-induced ketyl couplings are of significant synthetic interest, and Reissig el al. have reported an elegant application of the reaction in the case of the precursor 18. Reaction of 18 with 2 equivalents of samarium diodide and HMPA gave the 2-benzazepine 19 from an S-endo-dig cyclization reaction of the ketyl radical from the... 

Molander GA, George KM, Monovich JG. Total synthesis of (+)-isoschizandrin utiUziug a samarium(II) iodide-promoted 8-endo ketyl-olefin cyclization. J. Org. Chem. 2003 68 (25) 9533 9540. 

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