Tandem ring-opening/cyclocondensation reactions of 3-bromoisoxazoles

ORGN 662

Martin G. Kociolek, mgk5@psu.edu1, Nicholas G. Straub1, Jolene V. Schuster, Jolene.V.Schuster@Dartmouth.edu2, Elizabeth J. Marton1, and Jason W. Shaffer1. (1) Science, Penn State Erie, The Behrend College, 31 Hammermill Building, 5091 Station Road, Erie, PA 16563-0107, (2) Chemistry Department, Dartmouth College, HB 6128, Hanover, NH 03755
Isoxazoles have long been recognized as versatile synthetic intermediates for the construction of a variety of 1,3-difunctionalized compounds. Previously, we demonstrated that 3-bromoisoxazoles can be cleaved with molybdenum hexacarbonyl or ferrous chloride to give 2-cyanoketones. Recently, we have been able to extend this reaction to bromoisoxazoles substituted with an aldehyde-containing tether. These bromoisoxazoles readily undergo iron-mediated ring opening and subsequent cyclocondensation to yield a number of different sized carbocycles and heterocycles. We will report on the successful application of this tandem methodology to the synthesis of 5, 6 and 7-membered cycloalkenones and benzofused cycloalkenones. In addition, we will discuss our progress toward the synthesis of monocyclic and benzofused cyclic ethers, including a discussion of the application of this method to the synthesis of benzoxepin-containing natural products.
 

New Reactions and Methodology
1:00 PM-5:00 PM, Wednesday, 16 March 2005 Convention Center -- Ballroom 20 C-D, Oral

Division of Organic Chemistry

The 229th ACS National Meeting, in San Diego, CA, March 13-17, 2005