Experimental and DFT studies of the thermal rearrangement of 1,2-dialkynylimidazoles

ORGN 154

Christophe Laroche, christophe-laroche@hotmail.fr, Division of Medicinal Chemistry, University of Texas at Austin, College of Pharmacy, Austin, TX 78712 and Sean M. Kerwin, skerwin@mail.utexas.edu, Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712.
1,2-Dialkynylimidazoles undergo thermal rearrangement to cyclopentapyrazine carbenes, which can be trapped through inter- or intramolecular C-H insertion or olefin addition. A proposed reaction cascade for this rearrangement involves aza-Bergman rearrangement of the dialkynylimidazole to tetradehydro-1,4-diazonine, which undergoes a transannular cyclization to the cyclopentapyrazine carbene. We have prepared a series of 1,2-dialkynylimidazoles bearing electron-withdrawing and electron-donating substituents and studied the kinetics of their thermolysis in 1,4-cyclohexadiene. This work has two main goals: First, to be able to modify the reactivity of 1,2-dialkynylimidazoles towards thermolysis and carbene generation, and second, to compare these experimental results with computational studies at the DFT level in order to derive a model for predicting the facility of the thermal rearrangement of these compounds.
 

Physical Organic Chemistry, Combinatorial and Process Chemistry, New Reactions and Methodology, Peptides, Proteins and Amino Acids
8:00 PM-10:00 PM, Sunday, April 6, 2008 Morial Convention Center -- Hall A, Poster

Division of Organic Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008