Formation of organomagnesium compounds via EtMgBr-mediated radical cyclization of allyl β-iodoacetals

Organic Letters

Volumn 2, Issue 5, 2000, Pages 651-653

  Inoue, Atsushi ^a   Shinokubo, Hiroshi ^a   Oshima, Koichiro ^a  

^a KYOTO UNIVERSITY   (Japan)

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[No Author keywords available]

Indexed keywords

EID: 0000679160     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol991403a     Document Type: Article

References (39)

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28. 1,2-Elimination reaction of vicinal iodoalkoxyalkane with n-BuLi or n-BuMgBr has been reported. See ref 3e.
29. Experimental procedure is as follows. Under reduced pressure, solvent was removed from an ethereal solution of EtMgBr (3.0 mL, 1.0 M, 3.0 mmol). The residual solid was'dissolved in 5 mL of DME. To the mixture was added a solution of 7a (354 mg, 1.0 mmol) in DME (2 mL) at room temperature. After being stirred for 30 min, allyl bromide (0.26 mL, 3.0 mmol) and a THE solution of CuCN·2LiCl (0.3 mL, 1.0 M, 0.3 mmol) were successively added. The reaction mixture was stirred for 1 h at room temperature. After usual workup, purification by silica gel chromatography afforded the corresponding allylated product in 73% yield.
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33. Treatment of iodide 3 with EtMgBr in THF afforded the reduced product 2 quantitatively.
34. Using degassed THF, this radical cyclization reaction proceeded as smoothly as the reaction in THF which was not degassed and contained small amounts of oxygen. Thus, the presence or absence of oxygen in the solvent does not affect the reaction pathway.
35. 2Mg in this radical reaction.
36. 2 also provided cyclization product. Therefore, it is unlikely that traces of Mg metal in Grignard solution induce this radical process.
37. Newcomb, M.; Curran, D. P. Acc. Chem. Res. 1988, 21, 206 and references therein.
38. Formation of the cyclized alkene in THF (Table 1, entries 3 or 5) could be explained by elimination of hydrogen iodide from cyclic iodide.
39. -1). See ref 15 and references therein.