SYNTHESIS OF BIOLOGICALLY ACTIVE COMPLEX MOLECULES

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This revised grant application details our plans to utilize, based upon preliminary findings, a cascade reaction in which a vinyl organometallic addition to a ketone initiates an apparent anionic oxy-Cope rearrangement followed by a transannular cyclization. This three step tandem reaction is capable of converting simple cyclic 2-vinyl-beta-ketoesters to complex polycyclic structures in a single transformation. Bridgehead olefin-containing molecules, medium-size rings, and complex fused ring systems are all accessible using this reaction. On the basis of these results, our specific aims involve: (1) Elucidation of the mechanism of this process using stereochemical probes. (2) Studies to explore the generality of the cascade sequence with applications to the synthesis of bridgehead olefin- containing molecules, medium-size rings, and fused ring systems. The conversion of the medium-size ring systems to fused bicyclic structures via transannular cyclizations will also be explored. (3) Application of the cascade reaction to the total synthesis of the ras farnesyltransferase inhibitors CP-225,917 and CP-263,114. These molecules are currently undergoing testing as inhibitors of tumor progression and a concise synthetic route will provide access to variants for biological evaluation.