synthesys (Stranger)
03-23-03 11:13
No 420529
      LabTop's borohydride technique  Bookmark   

I have recently read some dated posts about a technique used in the borohydride reduction of P2P. The brohydride was combined with methanol and MeNH2 first, and then the P2P was dripped in using an addition funnel. Under inert atm.

Would this be the best technique to avoid borohydride exposure to air?

If you adapt this method to xxMA production, then could you:

1) isolate imine
2) combine borohydride/MeOH/MeNH2
3) attach addition funnel with imine
4) introduce inert atm
5) start dripping in imine

I read a lot of posts here on this topic, and oppinions of work up & yield seem to vary quite a bit.

LabTop, if you are out there, please comment on the work up some more.
 
 
 
 
    Rhodium
(Chief Bee)
03-23-03 11:24
No 420536
      Borohydride  Bookmark   

Borohydride is not especially air sensitive, and as long as you are working with methylamine, water is not a big problem either, as you can see in ../rhodium/chemistry /redamin.aqueous.nabh4.html
 
 
 
 
    Sunlight
(Pioneer Researcher)
03-26-03 15:50
No 421547
      Don't complicate it  Bookmark   

First mix your ketone with alcoholic methylamine, coll it and at 5 C more or less add the borohydride, slowly, let cool and add a bit more, cooling, don't let temp go higher than 15 C or so, an ice/salt bath works fine if you are not working with big amounts.
Don't add the borohydride to the methanol and then drop the imine, NaBH4 reacts immediatly with the methanol.