Identify the alkene that would react with Ti(OiPr)₄, (+) -diethyltartrate, and t-butylhydroperoxide to give the following chiral, nonracemic epoxides.
(a)

Verified step by step guidance

1. Understand the reaction: The Sharpless epoxidation is used to convert alkenes into epoxides using a chiral catalyst system. The reagents Ti(OiPr)₄, (+)-diethyltartrate, and t-butylhydroperoxide are part of this system.
2. Identify the stereochemistry: The product is a chiral, nonracemic epoxide, indicating that the reaction is stereoselective. The stereochemistry of the epoxide is determined by the chiral catalyst used.
3. Analyze the structure: The given epoxide has a specific stereochemistry at the epoxide ring. The stereochemistry of the starting alkene will influence the stereochemistry of the epoxide.
4. Determine the alkene structure: The alkene that would lead to the given epoxide must have a similar carbon skeleton. Look for the alkene that matches the carbon framework of the epoxide, excluding the oxygen atoms.
5. Consider the regioselectivity: The position of the double bond in the alkene will determine where the epoxide forms. Ensure the double bond is positioned correctly to form the epoxide at the desired location.

Key Concepts

Alkene Reactivity

Alkenes are hydrocarbons that contain at least one carbon-carbon double bond. Their reactivity is primarily due to the presence of this double bond, which can undergo various reactions, including electrophilic additions. Understanding the structure and stability of alkenes is crucial for predicting their behavior in reactions, especially when forming cyclic structures like epoxides.

Epoxidation

Epoxidation is a chemical reaction that converts alkenes into epoxides, which are three-membered cyclic ethers. This reaction can be facilitated by various reagents, including peracids and metal catalysts. The stereochemistry of the alkene and the conditions of the reaction can influence the configuration of the resulting epoxide, making it essential to consider these factors when predicting the product.

Chirality and Nonracemic Products

Chirality refers to the property of a molecule that makes it non-superimposable on its mirror image, leading to the existence of enantiomers. Nonracemic products are those that do not have equal amounts of both enantiomers, resulting in optical activity. In the context of the question, understanding how the reaction conditions and starting materials influence chirality is vital for identifying the correct alkene that yields a specific chiral epoxide.