One-pot formation and functionalization of di-, tri- and tetraynes

ORGN 616

Rik R. Tykwinski, rik.tykwinski@ualberta.ca1, Thanh Luu, thanh_derrek@yahoo.ca1, Yasuhiro Morisaki, ymo@chujo.synchem.kyoto-u.ac.jp2, and Wesley A. Chalifoux, wesleyc@ualberta.ca1. (1) Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada, (2) Department of Polymer Chemistry, Kyoto University, Yoshida, Sakyo-ku, Kyoto, 606-8501, Japan
The synthesis of triynes and unsymmetrical tetraynes is challenging because the usual Cu-catalyzed homocoupling techniques (Glaser, Hay, Eglinton/Galbraith) are not suitable, and a Cadiot-Chodkiewicz cross-coupling requires the prior synthesis of a terminal alkyne as one or both of the precursors. We have developed a “one-pot” procedure that allows for the formation of a polyyne framework and terminal functionalization in a single step. This approach involves the in situ formation of a lithium-acetylide directly from a dibromoolefin precursor and trapping with electrophiles to form, for example, propargyl or homopropargyl alcohols and acetylenic carboxylic acids. Alternatively, the Li-intermediate can be transmetalated to provide nucleophilic coupling partners for elaboration via Pd-catalyzed cross-coupling reactions. Thus, transmetalation to zinc followed by Negishi coupling with an aryl halide provides unsymmetrical aryl triynes, whereas transmetalation to tin followed by Stille coupling with an acid chloride gives ynones. The latest results from this study will be presented.

 

Modern Acetylene Chemistry
8:15 AM-12:00 PM, Wednesday, 13 September 2006 Moscone Center -- Room 134, Oral

Division of Organic Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006