Exam 12: The Chemistry of Ethers, Epoxides, Glycols, and Sulfides

Outline the synthesis of dicyclopentyl ether using alkoxymercuration-reduction.

Outline a multistep synthesis of the given alkene from acetylene and any other reagents. You must use the following reagents at one or more points in your synthesis (as well as other reagents). Note: These are not necessarily used at the same step. Show the organic products (not the reactive intermediates or by-products) resulting from each step.

Complete the diagram by supplying structures for all the missing compounds.

a. Only one of the two diastereomers (formula C₁₂H₂₃OBr) will react with NaOH to form a product X with the formula C₁₂H₂₂O. Identify the reactive diastereomer by circling it and labeling it with the letter A. Draw the product X in its chair conformation. b. The other diastereomer (B) reacts more slowly but eventually forms a product Y (C₁₂H₂₄O₂). Compound Y is not an alkene. Propose a structure for Y. c. Explain why compounds A and B react differently and explain why the formation of X from A is much faster than the formation of Y from B.

Benzo[a]pyrene is a carcinogenic polyaromatic hydrocarbon found in cigarette smoke that is converted by enzymes in the body to a diol epoxide. This diol epoxide product can react with nucleophiles on DNA and thus promote cancer. (This is one of the main reasons that cigarette smoke is carcinogenic.) The body can neutralize this toxin by reacting it with glutathione, a thiol. Representing glutathione as R-SH, show two products that might form when glutathione reacts with the diol epoxide, including their stereochemistry. Although acids and bases for this reaction are typically provided by the enzymes that catalyze this transformation, assume that -OH is the base and H₂O is the acid where acids and bases are necessary.