Investigation of the metal-halogen exchange reaction of a bromobenzo[b]thiophene

ORGN 145

Gabrielle R. Kolakowski, gkolakowski@icos.com1, Ramesh A. Kasar1, Musong Kim2, Kyla L. Bjornson1, Irina Jacobson3, Francine S. Farouz3, and Eugene D. Thorsett3. (1) ICOS Corporation, 22021 20th Ave SE, Bothell, WA 98021, (2) Department of Chemistry, University of Michigan, 930 N. Univeristy, Ann Arbor, MI 48109, (3) ICOS Corp, 22021 20th Ave SE, Bothell, WA 98021
An isomerized product was observed in the sequential lithiation and formylation of 5-bromobenzo[b]thiophene 1. Through NMR experiments, the sole product identified in a high yield was the benzo[b]thiophene-2-carboxaldehyde 3 rather than the expected 5-carboxaldehyde 2. The 2-carboxaldehyde 3 resulted from the facile formation of the 2-lithiobenzo[b]thiophene, rather than the 5-lithiobenzo[b]thiophene, which is the species expected to be formed in a metal-halogen exchange. Experimental evidence is described for the proposed product structure and possible mechanism of formation.

 

Heterocycles, Aromatics, Materials, Devices, Switches, Combinatorial Chemistry, Metal-Mediated Reactions
8:00 PM-10:00 PM, Sunday, 13 March 2005 Convention Center -- Hall D, Poster

Division of Organic Chemistry

The 229th ACS National Meeting, in San Diego, CA, March 13-17, 2005