Journal of the American Chemical Society · 2007 · 77 citations · 14 references
Natural SciencesChemistryCatalysisOrganic ChemistryOrganometallic ChemistryCoordination ChemistryCross-coupling ReactionsHeterocycle SynthesisHeterocyclic ChemistryHeterocyclic CompoundsOrganometallic SynthesisCopper-catalyzed CouplingRing-closure ReactionsRing-forming ReactionsTransition Metal-catalyzed SynthesisTransition-metal-catalyzed FunctionalizationTransition-metal-catalyzed Heterocycle Synthesis
The copper-catalyzed intramolecular O-vinylation of γ-bromohomoallylic alcohols was investigated. With 10 mol % of CuI as the catalyst and 20 mol % of 1,10-phenanthroline as the ligand, the reactions of 3-bromo-3-buten-1-ols in refluxing CH 3 CN led to the convenient formation of the corresponding 2-methyleneoxetanes in good to excellent yields via a 4- exo ring closure. The configuration of the C C bond was nicely retained. This methodology was then successfully extended to the cyclization in 5- exo, 6- exo, and even 6- endo modes. Moreover, the competition experiments revealed that 4- exo cyclization is fundamentally preferred over other modes of cyclization. On the other hand, the corresponding Pd(0)-catalyzed O-vinylation showed the predominance of 5- exo over 4- exo cyclization.
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