Synthesis of a New Class of Carborane-Containing Star-Shaped Molecules via Silicon Tetrachloride Promoted Cyclotrimerization Reactions Barada Prasanna Dash, † Rashmirekha Satapathy, † John A. Maguire, ‡ and Narayan S. Hosmane* ,† Department of Chemistry and Biochemistry, Northern Illinois UniVersity, DeKalb, Illinois 60115-2862, and Department of Chemistry, Southern Methodist UniVersity, Dallas, Texas 75275-0314 hosmane@niu.edu Received March 24, 2008 ABSTRACT Symmetrical star-shaped molecules with carborane clusters on the periphery have been synthesized in good yields via silicon tetrachloride mediated cyclotrimerization reactions of 9-benzyl derivatives of carboranes with acetyl group substitution on the benzene ring. Facile functionalization of these symmetrical core structures with 1-iodoheptane and trivinylchlorosilane produce compounds which could be used as liquid crystalline substances and precursors for synthesis of higher order carbosilane dendrons. Polyhedral carborane clusters are a class of synthetically useful molecules that have practical applications in areas such as materials science, medicine, and catalysis. 1 They have been widely used in making new boron neutron capture therapy (BNCT) drugs 2 and, more recently, in the syntheses of macromolecular structures such as dendrimers, 3 liquid crystalline substances, 4 and thermally stable polymers. 5 Dendrimers are globular macromolecules consisting of a symmetrical core and layers of branched repeating units extending from the core and end groups on the outer layer of the repeating units. These branched macromolecules have found applications as low-dielectric materials, catalysts, † Northern Illinois University. ‡ Southern Methodist University. (1) Zhu, Y.; Cheng, K. Y.; Maguire, J. A.; Hosmane, N. S. Curr. Chem. Biol. 2007, 1, 141–149. Hawthorne, M. F.; Mderna, A. Chem. ReV. 1999, 99, 3421–3434. Plesek, J. Chem. ReV. 1992, 92, 269–278. Teixidor, F.; Vinas, C.; Demonceau, A.; Nunez, R. Pure Appl. Chem. 2003, 75, 1305– 1313. Grimes, R. N. J. Chem. Educ. 2004, 81, 657–672. Salt, C.; Lennox, A. J.; Takagaki, M.; Maguire, J. A.; Hosmane, N. S. Russ. Chem. Bull. Int. Ed. 2004, 53, 1871–1888. ORGANIC LETTERS 2008 Vol. 10, No. 11 2247-2250 10.1021/ol8005248 CCC: $40.75 © 2008 American Chemical Society Published on Web 05/09/2008