Barium
(Hive Addict)
03-31-03 10:36
No 422798
      On route to 5-MeO-alpha-MT
(Rated as: excellent)
 Bookmark   

5-Methoxy-1H-indole-3-carbaldehyde 50 mmol, 8,75 g
Nitroethane 75 mmol, 5,6 g
Methylamine 10 mmol, generated from 0,675 g methylamine HCl and 0,4 g NaOH
IPA 50 ml

All was added to a rb flask and warmed to 50C on a water bath with stirring for 1 hour. The color changed from a dirty yellow at the beginning to a deep orange yellow during the reaction. When the reaction was over the flask was cooled to 0C for 15 minutes. This gave the nitroalkene as a solid cake in the flask. Just enough IPA to make the suspension stirable was added.

KBH4 75 mmol, 4,2 g, dissolved in 40 ml water containing 30 mg NaOH.

To the stirred suspension of the nitroalkene the potassium borohydride solution was added dropwise. During the addition of the first couple of milliliters the temperature rose from 8 to 14. This exotherm is from the unreacted aldehyde being reduced by the borohydride. As soon as this aldehyde is consumed the temperature remains stable at 14C during the remaining addition. The suspended nitroalkene gradually went into solution during the reaction. When all borohydride had been added the solution was allowed to stir for another 30 minutes at room temp. 100 ml cold water was added followed by GAA dropwise to destroy the remaining borohydride. Whan the gas evolution ceased the yellow solution was added to 600 ml cold water and left for 1 hour. The yellow crystalline solid was isolated by filtration and dried to constant weight.

Yield 6 g 5-methoxy-3-(2-nitropropyl)-1H-indole (51%)

Next I wil try to reduce this to 5-MeO-alpha-MT using the KCOOH-Pd/C CTH system.

Freaky
 
 
 
 
    GC_MS
(Hive Addict)
05-01-03 13:33
No 430662
      KBH4  Bookmark   

Is there a reason for choosing KBH4 instead of NaBH4 (like sodium-sensitive reaction?), or is it just to demonstrate its usefulness?

The faster you run, the quicker you die.
 
 
 
 
    Barium
(Hive Addict)
05-02-03 09:39
No 430870
      Reason  Bookmark   

No, there was no other reason than me being too lazy to open a fresh bottle of sodium borohydride when I had a alredy opened bottle of potassium borohydride on the table.tongue In the reduction of C=C bonds in nitrostyrenes any type of watersoluble borohydride can be used.

Freaky
 
 
 
 
    GC_MS
(Hive Addict)
05-04-03 15:48
No 431375
      analytical data  Bookmark   

Did you measure any analytical data to support your findings, such as melting point or mass spectrometrical information?

I have tried to synthesize DMT for the first time, following your route. The synthesis of indole-3-carboxyaldehyde via DMF/POCl3 was no problem, and MS indicated the aldehyde as only substance (minor indole impurity, less then 1%). However, once I subject the aldehyde to an aqueous MeNH2-catalyzed Henry reaction, I run into problems.
Dissolving indole-3-carboxaldehyde and MeNO2 in IPA gives a yellow solution; once I add MeNH2, the solution turns dark brownish/black. When I add an alkaline KBH4 solution, I notice yellow solids being formed. Drying the formed solids and subjecting them to GC/MS results in alot of crap. Alot of indole-3-carboxaldehyde, a major high MW impurity (M+ = 282) and also a substance with M+ = 156, which I tentatively identified as the condensation product of indole-3-carboxaldehyde and MeNH2. I'm pretty sure the high MW impurity is formed due to the presence of the aldehyde-MeNH2 condensation product.
But why is this? I don't think that I added to much MeNH2 (50 mmol indole-3-carboxaldehyde and 1.55 mL aq MeNH2 20%), and I allowed the reactions to proceed long enough. The aq MeNH2 was not freshly prepared, but it is properly stored so I don't see why that could form a problem. Any suggestions?

The faster you run, the quicker you die.
 
 
 
 
    GC_MS
(Hive Addict)
05-07-03 01:27
No 431892
      MeNH  Bookmark   

OK, there was something very wrong with my aq MeNH2....

I have a commercial 40% MeNH2 stock which I diluted to 20% with dH2O and stocked it at the same place as my 40% commercial solution. I applied this self-diluted solution several times in Ba's procedure for nitrostyrenes, with success! But this week, everything I do with it this week fails miserably. I don't understand... The formed substances make me think that the concentration of applied catalyst is to high, but that is in contrast with me (re)calculations.
But well, when preparing the catalyst by dilution from the commercial stock just before the reactions starts seems to work and I think considering to always do it that way.
I reperformed Ba's procedure for alpha-methyltryptamine. So far, everything looks OK. Just one step left to reduce the nitro to an amine and harvest the alpha-MT wink

The faster you run, the quicker you die.
 
 
 
 
    Barium
(Hive Addict)
05-07-03 03:04
No 431903
      Good  Bookmark   

It seems like you've had one of "those" weeks indeed.

When performing the indole-3-carboxaldehyde/nitromethane condensation the reaction mixture does get very very dark. I thought something was wrong the first couple of times I ran it. But from that ugly dark mixture one should be able to harvest gold colored crystals.

Freaky