Electrophilic additions to pyrroles promoted by a π-basic tungsten fragment

ORGN 382

Kevin D. Welch, kdw9e@virginia.edu1, William H. Myers2, Michal Sabat, ms5c@virginia.edu1, and W. Dean Harman1. (1) Department of Chemistry, University of Virginia, Charlottesville, VA 22904, (2) Department of Chemistry, University of Richmond
The ability to control the selectivity of additions and substitutions to the pyrrole ring is vital for the use of pyrroles as synthons for larger biologically active targets. The metal fragment {TpW(NO)(PMe3)} (Tp = hydridotris(pyrazolyl)borate) forms an η2-2,5-dimethylpyrrole complex which is activated towards electrophilic addition. The bound pyrrole exhibits three distinct, regioselective modes of reactivity: addition to the nitrogen of the pyrrole ring; addition to the β-carbon of the pyrrole ring; and [3+2] dipolar cycloaddition through the transient formation of an azamethine ylide intermediate. This methodology has been used to selectively synthesize β-alkylpyrroles and 7-azanorbornenes from the η2-2,5-dimethylpyrrole complex in one step.
 

Bioorganic, Metal-Mediated Reactions, and Molecular Recognition
8:00 PM-10:00 PM, Tuesday, 30 August 2005 Washington DC Convention Center -- Hall A, Poster

Division of Organic Chemistry

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