Novel copper-mediated cycloaromatization of electron-poor diarylethynylbenzenes to form benzo[a]fluoren-11-ones

ORGN 771

Thomas S. Hughes, Thomas.S.Hughes@uvm.edu, Department of Chemistry, University of Vermont, Cook Physical Sciences Building, 82 University Place, Burlington, VT 05405 and Arun E. S. Thamban, QD Vision Inc, 313 Pleasant St, Watertown, MA 02472.
A novel tandem cycloaromatization reaction has been shown to convert an electron-poor 1,2-di(arylethynyl)benzene to a benzo[a]fluoren-11-one as shown. The diyne was easily synthesized by successive Sonogashira cross-couplings. Reaction of the diyne with copper iodide an methanol in DMF gave a precedented cyclization to an isochromene product, but exclusion of methanol gave the novel rearrangement product. The structure of the polyaromatic product was determined by 2-D NMR spectroscopy, including COSY, HMBC and HMQC techniques. The mechanism of the reaction has been investigated, and analogs of the nitroaldehyde starting material have been subjected to the reaction conditions. Both copper iodide and DMF appear to be required for the rearrangement to proceed.

 

Combinatorial, Parallel and Process Chemistry, Heterocycles, Aromatics, New Reactions and Methodology
8:00 PM-10:00 PM, Wednesday, August 22, 2007 BCEC -- Exhibit Hall - B2, Poster

Division of Organic Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007