acx01b
Hazard to Self
Posts: 59
Registered: 6-5-2004
Member Is Offline
Mood: No Mood
|
|
imine + R-O-R-MgX
Hi,
I would like to know if you think that the following reaction will work :
acetone + aniline ---- (molecular sieves 4a, cyclohexane) ---> isopropyl anilimine
CH3-CO-CH3 + Ph-NH2 -----> (molecular sieves 4a, cyclohexane) ----> CH3-C(=N-Ph)-CH3
bromomethyl methyl ether + Mg ----> (THF) ----> bromo magnesium methyl methyl ether
Br-CH2-O-CH3 + Mg ----> (THF) ----> BrMg-CH2-O-CH3
isopropyl anilimine + bromomagnesium methyl methyl ether ----> (H2O) ----> N-isopropyl alpha-methyl methyl ether aniline
CH3-C(=N-Ph)-CH3 + BrMg-CH2-O-CH3 ----> (H2O) ----> CH3-C(CH2-O-CH3)(-NH-Ph)-CH3
I have an other question : why in some synthesis reacting organometallics with imine is done with organolithium and not with organo magnesium. In the
reaction I describe will it be better to use Li-CH2-O-CH3 ???
Thank you very much !!
Reno
[Edited on 14-2-2012 by acx01b]
[Edited on 14-2-2012 by acx01b]
[Edited on 14-2-2012 by acx01b]
|
|
|
acx01b
Hazard to Self
Posts: 59
Registered: 6-5-2004
Member Is Offline
Mood: No Mood
|
|
I got some reference on the fact that CH3-O-CH2-MgBr is very unstable, and should be formed and kept at -20°C.
I am going to open a new thread to discuss the unstability of CH3-O-CH2-MgBr
|
|
|
acx01b
Hazard to Self
Posts: 59
Registered: 6-5-2004
Member Is Offline
Mood: No Mood
|
|
unstability of CH3-O-CH2-MgBr
Hi,
I found only one paper where they use the organomagnesium obtained from bromomethyl methyl ether and magnesium in THF.
CH3-O-CH2-Br + Mg ----> CH3-O-CH2-MgBr
I think that there are two possibilities of destruction of CH3-O-CH2-MgBr
rearrangement
CH3-O-CH2-MgBr ---> CH3-CH2-O-MgBr
In that case, the temperature should be kept under -20°C during all the reaction.
bimolecular reaction
CH3-O-CH2-MgBr + CH3-O-CH2-Br ----> CH3-O-CH2-CH2-O-CH3 + MgBr2
In that case, after all the CH3-O-CH2-Br has been converted to CH3-O-CH2-MgBr, this reaction cannot occur anymore, and so it can go back to positive
ambient temperature.
What do you think ? What reaction will occur ? Is there an other reaction that I didn't think of ?
Thank you very much !
|
|
|
GreenD
National Hazard
Posts: 623
Registered: 30-3-2011
Member Is Offline
Mood: Not really high anymore
|
|
I'm sure it has to do with the Mg wanting that oxygen atom, and so close to an electronegative carbon, You will probably get some kind of bimolecular
reaction, yes.
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
I would tend to believe that such alpha-alkoxyorganomagnesium compounds relatively rapidly decompose into the corresponding carbenes and then further.
What you call a "bimolecular reaction" can not occur as it requires methoxymethyl bromide. That is not a decomposition, but a reaction.
|
|
|
Nicodem
|
Threads Merged
15-2-2012 at 11:52 |
acx01b
Hazard to Self
Posts: 59
Registered: 6-5-2004
Member Is Offline
Mood: No Mood
|
|
Hello all,
I finally founded a good reference about imines and organo metallics ! Not so easy to find, and it contains many answers.
http://www.chemistry.sc.chula.ac.th/course_info/OrgReact05/F...
The imine R-MgBr reaction will never work, with R-Li it is maybe possible with BH3 as Lewis basis neutralizer, but there is only a little chance !
Most imine / R-Li additions are difficult to perform.
| Quote: |
What you call a "bimolecular reaction" can not occur as it requires methoxymethyl bromide. That is not a decomposition, but a reaction.
|
It can occur when you add the Mg to the methoxymethyl bromide !
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
