Saturday, October 27, 2007
Ballroom Posters (Greenville Hyatt Regency Hotel)
822

Towards a New Synthetic Method for the Synthesis of Carboxamidines from Carboxamides

B. Chadwick LeCroix and David J. A. Schedler. Birmingham-Southern College, Birmingham, AL

Previous work has shown that zirconium (IV) and aluminum enolates of carboxamides can be selectively reduced using either Cp2-ZrHCl or DIBAL to yield N-substituted imines in one step. This work demonstrated the efficient reductive deoxygenation of carboxamides using hydride nucleophiles. In this regard, our group envisioned that the use of other nucleophiles besides hydrides could lead to a whole new synthetic method towards medicinally important substituted imines. These new methods would simplify the synthesis of these important molecules and allow them to be easily modified to optimize their efficacy. To this end our research has been directed at investigating whether reactions of nitrogen nucleophiles to these metal enolates could lead to the formation of carboxamidines. This led to research into the reaction of amines or lithium amides, i.e. lithium diisopropylamide (LDA), with zirconium and aluminum enolates of caboxamides to form the corresponding carboxamidines. Generally, this is accomplished by first converting the carboxamide to the organozirconium or organoaluminum enolate by treatment with 1.2 eq. of ZrCp2HCl or DIBAL at -20 ºC in THF. The resulting enolate is then be treated with 1.5 eq. of an amine or lithium amide to yield the carboxamidine. To date, we have seen evidence of success with the reaction of the aluminum enolate of benzanilide with LDA. Reported will be the preliminary results towards the optimization of this new synthetic method.