Question

Fill in the lettered products (A–D) in the synthesis of (R)-isoproterenol, a drug that increases heart rate and dilates lung passages.

Short answer

Answer

For the synthesis of (R)-isoproterenol, the reaction scheme is shown below:-

Step-by-step solution

Step-by-Step Solution Step 1: Function of CBS

CBS is a chiral reducing agent. They are a boronic compound that functions as an asymmetric reduction and forms enantiomeric alcohols.

Here (R)-CBS is used which attacks the carbonyl carbon center position from the backside position and yields alcohol having an S-configuration where the alcohol group lies in the wedge position.

Function of NaI

NaI acts as a nucleophilic catalyst due to the presence of a powerful Iodide group that can create a nucleophilic attack.

Function of alkyl silyl chloride

Alkyl silyl chlorides are used for the protection of alcoholic groups.

Function of amines

Amines are used for nucleophilic substitution reactions.

Function of fluoride salts

Fluoride salts like potassium fluorides are used for the deprotection of alcoholic groups.

Hence, considering all the key points, the reaction scheme for the synthesis of (R)-isoproterenol is shown below:-