Exploiting the Diverse Chemistry of Boroles to Access Unsaturated Boracycles

Thursday, March 23, 2017


Dr. Caleb Martin

Department of Chemistry and Biochemistry

Baylor University

Dr. Caleb MartinAlthough boroles (1) were first reported in 1969, their reactivity has remained virtually unexplored until recently. The unique combination of a Lewis acidic tricoordinate boron center, a diene, and a strained planar BC4 five-membered ring in a single molecule coupled with the four π-electron anti-aromatic state results in highly diverse reactivity for boroles.1 Our group’s efforts have been focused on exploiting the chemistry of these species with the intent of utilizing boroles as reagents to generate six-, seven-, and eight-membered unsaturated boracycles (2-4).2 Conjugated boracycles are attractive synthetic targets as these species have applications in electronic devices and medicinal chemistry. Through these studies we have been able to prepare a diverse array heterocycles via the insertion of readily available substrates into boroles. This includes a new breed of benzene analogues (2) in which a C=C unit is replaced with boron and either a group 15 or group 16 element.3 The mechanisms of these reactions and properties of the boracycles will be discussed.

Reaction Scheme

 

Caleb Martin grew up in New Brunswick, Canada and attended Mount Allison University for his BSc. While there he worked with Glen Briand on indium chemistry and Steve Westcott on palladium catalysis. In 2007 he moved to Western University to work on chalcogen and phosphorus chemistry with Paul Ragogna. Upon graduation in 2011, he moved to the US to work for Guy Bertrand on carbene chemistry at UC San Diego. In 2013 he accepted a position at Baylor University.

References:

  1. J. H. Barnard, S. Yruegas, K. Huang, C. D. Martin, Chem. Commun., 2016, 52, 9985.
  2. a) K. Huang, C. D. Martin, Inorg. Chem., 2016, 55, 330. b) J. H. Barnard, S. Yruegas, S. A. Couchman, D. J. D. Wilson, J. L. Dutton, C. D. Martin, Organometallics, 2016, 35, 929. c) K. Huang, C. D. Martin, Inorg. Chem., 2015, 54, 1869. d) K. Huang, S. A. Couchman, D. J. D. Wilson, J. L. Dutton, C. D. Martin, Inorg. Chem., 2015, 54, 8957.
  3. a) J. H. Barnard, P. A. Brown, K. L. Shuford, C. D. Martin, Angew. Chem. Int. Ed., 2015, 54, 12083. b) S. A. Couchman, T. K. Thompson, D. J. D. Wilson, J. L. Dutton, C. D. Martin, Chem. Commun., 2014, 50, 11724. c) S. Yruegas, D. C. Patterson, C. D. Martin, Chem. Commun., 2016, 52, 11724.

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