Bismuth nitrate-catalyzed synthesis of pyrrole-substituted beta-lactams

ORGN 745

Isabella Garcia, banik@panam.edu and Bimal K. Banik, banik@panam.edu. Department of Chemistry, The University of Texas-Pan American, 1201 W. University Drive, Edinburg, TX 78541
Bismuth salts have become very popular in the synthesis of several organic compounds. There are a number of advantages of using bismuth salts. For example, most of them are commercially available, non-toxic and very economical. We have reported the use of bismuth nitrate in several organic transformations. In particular, recently we have demonstrated a facile method for the synthesis of substituted pyrroles. During the course of this study and in continuation of our endeavor for the synthesis and biological evaluation of novel beta-lactams, we develop a new pathway for the synthesis of beta-lactams that have a pyrrole ring at the C-3 position of the azetidinone ring in excellent yield. The reaction of 3-cis and trans amino beta-lactams with commercially available acetonyl acetone in the presence of catalytic amounts of bismuth nitrate in organic solvents has produced beta-lactams substituted with a pyrrole ring at the C-3 position. Although the chemistry of beta-lactams is extremely rich, methods for the preparation of pyrrole substituted azetidinones is not known. A few other acids including bismuth-derived reagents have also been tested. It has been found that the success of this reaction depends on the concentration of the catalyst loading and nature of the solvent.