[quantumnumber]

Hi guys,

I was thinking of the best route to synthesize 3-methoxybenzaldehyde from benzene or toluene. I have proposed a couple of theoretically logical options, but they consist on too many steps (7 or more)...
Any suggestions?
Thanks a lot.

[orgopete]

 :-[I don't think you can do it in two (steps, edit), so show us what you have and what you think are its defects.

[zsinger]

I would try ordering it .  Why do you need 3-methyoxybenzaldehyde?
           -Zack

[AromaticAcrobatic]

How about in 5 steps such as Freidel crafts acylation with methanoyl chloride, followed by bromination, then NaOH at 70°C in H3O, followed by NaH then Br-CH3.

[AromaticAcrobatic]

And of course my suggestion is starting with benzene..

[quantumnumber]

I would try ordering it .  Why do you need 3-methyoxybenzaldehyde?
           -Zack

It's a retrosynthetic excercise my teacher asked me to do... The point is that I'm not sure he really want me to start from bencene or toluene, but is what the formulation of the excercise said 

[quantumnumber]

this is what I thought first...

[quantumnumber]

How about in 5 steps such as Freidel crafts acylation with methanoyl chloride, followed by bromination, then NaOH at 70°C in H3O, followed by NaH then Br-CH3.

After the bromination, is that a nucleophilic aromatic substitution? I thought something like that, but the electron widrawing group should be at orto/para position from bromine to activate it, shouldn't it?

[AromaticAcrobatic]

Very good, good catch! 

Let me rethink the synthesis

[AromaticAcrobatic]

This is an awesome question. It's amazing how fast it went from being really easy to really complicated. Since this is a theoretical question, how about we increase the temperature for the nucleophilic substitution from 70°C to 350°C. 
I was looking through my book for a reaction I maybe forgot/wasn't covered when I took Organic and the increase in temperature seems to work without the need for an ortho/para electron withdrawing group.

[AromaticAcrobatic]

Looking back at your route, wouldn't the H2/Pd C after the acyalation also reduce the carbonyl s?

[quantumnumber]

Looking back at your route, wouldn't the H2/Pd C after the acyalation also reduce the carbonyl s?

You're right. I made a mistake. The catalytic hydrogenation must be done using platinum(IV) oxide (PtO₂) 

[orgopete]

@quantum
Since your route uses the sequence of nitration, reduction, diazotization, and hydrolysis, this introduces a hydroxyl group at the nitro. What kind of director is benzaldehyde? Might it be a useful target?

[quantumnumber]

AHHH, sorry, there is another step of nitration after reducing the first NO₂... I forgot to write it 
I added this second NO₂ to block that position and acylate at orto position from the amine.

[zsinger]

BUY IT! 
      -Zack