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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Sarvan_RTK on March 10, 2021, 11:52:38 AM

Title: Mechanism and Retrosynthesis
Post by: Sarvan_RTK on March 10, 2021, 11:52:38 AM

Mechanism and Retrosynthesis

I have a doubt from the book: Organic synthesis the disconnection approach (Stuart warren 2nd edition) on page 49. How primary alcohol (compound 60) reacts with an aldehyde and HCl to give the intermediate 61 and then cyclise to form 58. Please advise mechanism.

Title: Re: Mechanism and Retrosynthesis
Post by: rolnor on March 10, 2021, 01:25:50 PM

Can you post a picture? I dont think everyone has that book.

Title: Re: Mechanism and Retrosynthesis
Post by: Sarvan_RTK on March 11, 2021, 11:33:27 AM

Many Thanks. I posted the picture. Please advise me of the mechanism. How aldehyde and alcohol, and HCl give intermediate and form the final product. I could understand the last step. But I could not understand the first step. Please help.

Title: Re: Mechanism and Retrosynthesis
Post by: rolnor on March 11, 2021, 12:01:01 PM

The first step is similar to acetal formation but the chloride ion attacks instead of the alcohol in the second step:
https://en.wikipedia.org/wiki/Acetal

Title: Re: Mechanism and Retrosynthesis
Post by: Babcock_Hall on March 11, 2021, 04:08:22 PM

@OP, What are your thoughts?

Title: Re: Mechanism and Retrosynthesis
Post by: Sarvan_RTK on March 13, 2021, 07:21:28 AM

Thanks. Is there any chance to see the arrow pushing mechanism here? Is there any chance to see the arrow pushing mechanism here? 

Title: Re: Mechanism and Retrosynthesis
Post by: Babcock_Hall on March 13, 2021, 09:09:14 AM

Sarvan_RTK,

Please look at the forum rules (see red link above), and show us your work.  We can only help you after that.

Title: Re: Mechanism and Retrosynthesis
Post by: Sarvan_RTK on March 13, 2021, 07:07:56 PM

This looks like phenyl isochromane synthesis

Synthesis of isochromans via Fe(OTf)2-catalyzed Oxa-Pictet–Spengler cyclization

Title: Re: Mechanism and Retrosynthesis
Post by: rolnor on March 14, 2021, 06:44:39 AM

No, its rather a case of Friedel-Craft alkylation. I think you need a Lewis acid for the last step.