Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
 Pages:  1    3
Author: Subject: reductive amination with triacetoxyborohydride
Klute
International Hazard
*****




Posts: 1378
Registered: 18-10-2006
Location: France
Member Is Offline

Mood: No Mood

[*] posted on 5-9-2008 at 08:41


Good idea. My NaBH4 is already pretty finely divided, although it does cake up a little in the original bottle.. So I could just transfert it to my flask, apply vacuum, and heat in an oil bath with stirring to break down the lumps.. at which temp do you heat?



\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"

-Alice Parr
View user's profile View All Posts By User
grind
Hazard to Others
***




Posts: 120
Registered: 13-1-2007
Member Is Offline

Mood: No Mood

[*] posted on 5-9-2008 at 09:01


You can heat it to 150°C. The decomposition temperature is about 400°C, so 150°C are no problem. At first you should heat it cautiously, then with full power.
But I think it´s better to break down the lumps before heating it, because simple magnetic stirring doesn´t break down the lumps (my personal experience). Or you powder it when it´s covered with toluene, that´s another possibility.
View user's profile View All Posts By User
Klute
International Hazard
*****




Posts: 1378
Registered: 18-10-2006
Location: France
Member Is Offline

Mood: No Mood

[*] posted on 5-9-2008 at 09:09


This looks like a much better approach than adding the hydride to solvents: you hydride it entirely dry, aswell as your steup, and introducing dry solvents via syringe minimizes any contact with atmospheric moisture.. You really are the STAB Guru :)

I'm also considering trying to reduce the enamine with NaBH4 in AcOH, but adding the hydride to the enamine with 1 eq of GAA: of course, the reductant is NaBH4 here, not STAB, but at least all 4 hydrides can be used. Now that I knwo that STAB works for this particuliar substarte, i will try the NaBH4 (which is used in an enamine reduction procedure).

Apparently, with a similar substrate, using NaBH3CN with the carbonyl and the amine in MeOH gives only the alcohol, even though the enamine is readily formed, but preforming the enamine and reducing it it with NaBH3CN gives the expected product.

The Zn/GAA procedure has been pretty dirty and low yielding, but it could be du to the crude amide (I'm going to try it out with a cleaner amide).




\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"

-Alice Parr
View user's profile View All Posts By User
 Pages:  1    3

  Go To Top