In light of your answer to Assessment 8.73, predict the product of the following oxymercuration–reduction reactions, each of which results in a single product. [Don't worry about the absolute stereochemistry, though these reactions are also stereoselective.]
(c) Oxymercuration–reduction was used in the stereoselective synthesis of the macrolactone core of neopeltolide, a marine macrolide isolated from a Caribbean sponge that has potent anticancer activity (Org. Lett. 2012, 14, 2346–2349).

Verified step by step guidance

1. Identify the reaction type: The reaction shown is an oxymercuration-reduction, which is used to convert alkenes to alcohols without rearrangement.
2. Analyze the starting material: The structure provided is a complex macrolactone with an alkene group. The alkene is the site of the oxymercuration-reduction reaction.
3. First step - Oxymercuration: The alkene reacts with mercuric trifluoroacetate (Hg(OTFA)2) in the presence of water. This step forms a mercurinium ion intermediate, where the mercury atom is added to the less substituted carbon of the alkene, and a hydroxyl group is added to the more substituted carbon.
4. Second step - Reduction: Sodium borohydride (NaBH4) is used to reduce the mercurinium ion intermediate, replacing the mercury group with a hydrogen atom, resulting in the formation of an alcohol.
5. Predict the product: The final product will have an alcohol group at the more substituted carbon of the original alkene, maintaining the stereochemistry of the other substituents in the macrolactone core.

Key Concepts

Oxymercuration-Reduction

Oxymercuration-reduction is a two-step reaction used to convert alkenes into alcohols. In the first step, an alkene reacts with mercuric acetate in the presence of water, leading to the formation of a mercurial intermediate. The second step involves the reduction of this intermediate, typically using sodium borohydride, which replaces the mercury with a hydrogen atom, yielding an alcohol. This reaction is notable for its regioselectivity and stereoselectivity.

Regioselectivity

Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple possibilities exist. In the context of oxymercuration-reduction, the reaction typically follows Markovnikov's rule, where the more substituted carbon atom of the alkene becomes bonded to the hydroxyl group in the final alcohol product. Understanding regioselectivity is crucial for predicting the outcome of reactions involving alkenes.

Stereoselectivity

Stereoselectivity is the property of a reaction to favor the formation of one stereoisomer over others. In oxymercuration-reduction, the reaction can lead to the formation of specific stereoisomers due to the nature of the intermediate and the subsequent reduction step. Although the question specifies not to worry about absolute stereochemistry, recognizing that the reaction can produce different stereoisomers is important for understanding the overall product distribution.