91Ó°ÊÓ

Question: Devise a stepwise mechanism for the following reaction, a key step in the synthesis of the antibiotic abyssomicin C. Abyssomicin C was isolated from sediment collected from almost 1000 ft below the surface in the Sea of Japan. (Hint: The mechanism begins with a Dieckmann reaction.)

Question: Draw the products formed in the crossed aldol reaction of phenylacetaldehyde $\left(C_6{H}_{5}C{H}_{2}CHO\right)$with each compound: (a) $\mathit{C}{\mathit{H}}_{\mathbf{2}}{\left(COOEt\right)}_{\mathbf{2}}$; (b) $\mathit{C}{\mathit{H}}_{\mathbf{2}}{\left(COC{H}_3\right)}_{\mathbf{2}}$; (c) $\mathit{C}{\mathit{H}}_{\mathbf{3}}\mathit{C}\mathit{O}\mathit{C}{\mathit{H}}_{\mathbf{2}}\mathit{C}\mathit{N}$.

Question: What aldol product is formed when two molecules of butanal react together in the presence of base? What reagents are needed to convert this product to each of the following compounds?