Synthesis of Fused Nitrogen Containing Heterocycles via Cascade Reactions

The synthesis of fused nitrogen heterocycles has been investigated. Chapter 1 describes the synthesis of quinolones through a copper catalyzed amide coupling to ortho acetyl aryl halide followed by an aldol condensation that produces the quinolone in modest to good yields. The reaction works well with lactam partners and leads to tricyclic ring systems. Chapter 2 describes the synthesis of 8 membered enamide rings through a [3,3] sigmatropic rearrangement ring expansion of N-vinyl β-lactams. The N-vinyl β-lactams also undergo a 6π electrocyclization following the [3,3] sigmatropic rearrangement to furnish amino cyclobutanes. Previously reported amino cyclobutanes have been made using [2+2] photocycloaddition and resulted in a mixtures of diastereoisomers. Our method produces the amino cyclobutanes in good to high yields and with excellent levels of diastereoselectivity. Chapter 3 describes the synthesis and applications of reduced hydantoins from aziridine aldehydes and isocyanates. The resulting heterocycles contain an aziridine ring fused to a 5 membered urea. We also demonstrate that the reduced portion of the hydantoin, namely the hydroxyl group, can undergo further displacement with β-ketoesters similar to iminium ion chemistry.Ph