New Synthetic Approaches to Heterohelicenes based on Catalytic Domino Cyclization

<strong>Seminar of the School of Physical Sciences -------------------------------------------------</strong> Title:<strong> New Synthetic Approaches to Heterohelicenes based on Catalytic Domino Cyclization</strong> Speaker: <strong>Irie Ryo</strong> (Kumamoto University, Kumamoto) Date:<strong> March 3, 2016</strong> <strong>Abstract: </strong>Extended π-conjugated heterocycles, in which heteroaromatic and aromatic rings are condensed alternately, have aroused enormous interest and have been exploited as components of photoelectronic devices [1]. In this context, it should be intriguing to investigate practical synthesis of heterohelicenes, angularly fused heteroaromatic compounds with helical chirality, for producing novel functional materials of chiroptical properties. Herein, we will report new synthetic approaches to unique heterohelicenes containing a dibenzofuran and a carbazole structure based on the palladium-catalyzed dehydrogenation [2,3] of aromatic diynes and base-catalyzed cycloisomerization [4,5] of o-alkynyl heterobiaryls. The stereochemical behaviour of the heterohelicenes thus obtained will be also presented on the basis of kinetic analysis as well as DFT calculations. 1. Y. Shen, C.-F. Chen, Chemical Reviews, 112(3), 1463-1535, 2012. 2. R. Irie, A. Tanoue, S. Urakawa, T. Imahori, K. Igawa, T. Matsumoto, K. Tomooka, S. Kikuta, T. Uchida, T. Katsuki, Chemistry Letters, 40(12), 1343-1345, 2011. 3. M. Furusawa, T. Imahori, K. Igawa, K. Tomooka, R. Irie, R. Chemistry Letters, 42(10), 1134-1137, 2013. 4. M. Furusawa, K. Arita, T. Imahori, K. Igawa, K. Tomooka, R. Irie, Tetrahedron Letters, 54(52), 7107-7110, 2013. 5. R. Irie, M. Furusawa, K. Arita, K. Igawa, K. Tomooka, Journal of Synthetic Organic Chemistry, Japan, 72(10), 1131-1142, 2014.