Stereoselective construction of spirolactams from arene ruthenium precursors

ORGN 714

F. Christopher Pigge, chris-pigge@uiowa.edu, Department of Chemistry, University of Iowa, 305 Chemistry Building, Iowa City, IA 52242 and Rashmi Dalvi, Department of Chemistry & Biochemistry, University of Missouri - St. Louis, One University Blvd, St. Louis, MO 63121.
Benzyl substituted β-amido phosphonates are converted to dearomatized azaspiro[4.5]decane derivatives. This transformation is accomplished via the intermediacy of η6-arene ruthenium(II) complexes. The increased electrophilicity of the coordinated arene ring results in facile intramolecular nucleophilic aromatic addition of the tethered amido phosphonate. Subsequent Wadsworth-Emmons olefination then delivers stable cyclohexadienyl ruthenium complexes. This tandem two-step sequence can be conveniently performed in one pot and is compatible with a number of aldehyde reaction partners (R'CHO). Removal of the transition metal fragment is achieved upon exposure of cyclohexadienyl complexes to mild oxidants (CuBr2) in the presence of suitable nucleophiles (e.g., MeOH). Metal-free spirolactams are isolated as single diastereomers. Demetalation performed under an atmosphere of CO permits recovery of the CpBrRu(II) fragment in the form of its dicarbonyl adduct.

 

Heterocycles and Aromatics
8:00 AM-12:00 PM, Thursday, 1 September 2005 Washington DC Convention Center -- Ballroom B, Oral

Division of Organic Chemistry

The 230th ACS National Meeting, in Washington, DC, Aug 28-Sept 1, 2005