The bengamides are a series of natural products that have shown inhibitory effects on

Chapter 3, Problem 3.65

(choose chapter or problem)

The bengamides are a series of natural products that have shown inhibitory effects on the enzyme methionine aminopeptidase, which plays a key role in the growth of new blood vessels, a necessary process for the progression of diseases such as solid tumor cancers and rheumatoid arthritis. During the synthesis of bengamides, it is often required to convert OH groups into other, less reactive groups, called protecting groups, which can be converted back into OH groups when desired. For example, compound 1 is protected upon treatment with compound 2 in the presence of compound 4 (Tetrahedron Lett. 2007, 48, 87878789). First, 1 reacts with 2 to give intermediate 3, which is then deprotonated by 4 to give 5: (a) Draw the structure of 5 and show a mechanism for its formation from 3. (b) Use a quantitative argument (pKa values) to verify that 4 is an appropriate base for this transformation. (c) Explain how you would use IR spectroscopy to verify the conversion of 1 to 5. OMe OMe OSiMe3 OSiMe3 O O O O O Me3Si H Me N Me = OH O Ph O Ph Ph Ph Ph Ph