Need help explaining this Albuterol diagram

[aznlouie408]

Hi all,

 

Can someone explain step 1 to 5 for me?? I'm trying to understand this reaction and I don't understand it.

 

Appreciated if you guys could give me a detail explanation of each step.

 

Please see below for the reaction diagram.

 

 

Thanks a lot!

 

-Louis

[Tartaglia]

Step I is a disguised aldol reaction

Step II is a ketal formation via dehydration. The ketone effectively acts as a protecting group

Step III is nucleophilic attack of (CH3)2S+-CH2- at the aldehyde, followed by ring closure to eliminate (CH3)2S and form the epoxide

Step IV is nucleophilic attack of amine on the less hindered epoxide carbon, resulting in ring opening

Step V is removal of the protecting ketone via acid hydrolysis