Annulenes have been the object of great interest for chemists for a long time. Correspondingly, our understanding of the various properties of annulenes – in particular aromatic and anti-aromatic ones – has increased dramatically since their initial discovery in the 19th century. Nevertheless, many questions remain unanswered regarding this class of compounds. Despite major advances in computational modeling, highly conjugated molecules such as annulenes remain challenging to model accurately and their properties need to be studied experimentally. We became intrigued by the possibility of inducing planarity in medium-sized annulenes through the fusion of cyclopropane rings on the periphery of the conjugated ring. Very little is known about planar medium-sized annulenes and the synthesis of such structures is therefore of fundamental interest. Our efforts, successes, and failures in the synthesis of [10]- and [12]annulenes will be presented.

References:

[1] Schleyer, P. v. R.; Jiao, H.; Sulzbach, H. M.; Schaefer, H. F., Highly Aromatic Planar all-cis-[10]Annulene Derivatives. J. Am. Chem. Soc. 1996, 118, 2093-2094.

Short Biography of the Speaker:

Michel Gravel obtained his B.Sc. (Pharmaceutical Chemistry) at the Université de Sherbrooke and his Ph.D. at the University of Alberta under the supervision of Prof. Dennis G. Hall. He then joined the group of Prof. Viresh H. Rawal at The University of Chicago for an NSERC postdoctoral fellowship. He joined the Department of Chemistry at the University of Saskatchewan in 2006 as an assistant professor, was promoted to associate professor in 2011, then to full professor in 2018. His research interests are in the areas of organocatalysis, conjugated molecules, and computational chemistry. He has received the College of Arts & Science Teaching Excellence Award (2011), the Chemistry Students’ Society Undergraduate Teaching Excellence Award (2011, 2016), and was nominated for a University of Saskatchewan Students’ Union Teaching Excellence Award (2023).