Chemoselectivity and Protecting Groups: Crash Course Organic Chemistry

The video explores the concept of protecting groups in organic chemistry, which are used to prevent certain functional groups from reacting during chemical transformations. It discusses the use of protecting groups for carbonyl compounds, alcohols, amines, and carboxylic acids, providing examples and criteria for selecting effective protecting groups. The video also covers the reduction of carbonyl compounds using different agents and highlights the importance of protecting groups in complex molecule synthesis.

What is the primary purpose of a protecting group in chemical reactions?

• To change the color of a compound

• To enhance the reactivity of a molecule

• To increase the molecular weight of a compound

• To prevent unwanted reactions of a functional group

Which reducing agent is known as the 'sledgehammer' for reducing carbonyl compounds?

• Lithium borohydride

• Lithium aluminum hydride

• Sodium borohydride

• Sodium hydride

What is the first criterion for a good protecting group?

• It should be easy to attach

• It should be colorful

• It should be expensive

• It should be heavy

What type of group is used to protect aldehydes and ketones?

• Acetal group

• Amino group

• Carboxyl group

• Hydroxyl group

Which of the following is a common protecting group for alcohols?

• Carboxylate

• Silyl ether

• Nitrate

• Amide

What is the advantage of using a benzyl group as a protecting group for alcohols?

• It is easily removed by bases

• It is resistant to acidic conditions

• It is colorful

• It is very reactive

What is the final step in removing a silyl ether protecting group?

• Cooling the compound

• Heating the compound

• Adding a base

• Adding acid or fluoride

Which protecting group is commonly used for amines?

• Carboxy benzyl group

• Acetal group

• Silyl ether

• Hydroxyl group

What is a key feature of the TERT butyl ester protecting group for carboxylic acids?

• It is colorful

• It is bulky and removed by acid

• It is very reactive

• It is removed by hydrogenation

In the synthesis of penicillin, why is the ring-closing step saved for last?

• The ring is very reactive

• The ring is heavy

• The ring is colorful

• The ring is sensitive to hydrolysis