Hello.
I have this Di Boc protected bromo amino pyridine (see attached mechanism). I want to do a metal-halogen exchange using iPrMgCl and react this with methylchloroformate to yield the methyl ester. My compound is dissolved in THF and the grignard reagent added dropwise (1,2 eq.) @ 0 C. After around 45 min., my spot has gone up instead of down on my TLC plate. Normally it goes the other way around, as I quench it, giving it a proton. Since it gets more hydrophobic on TLC I guess that I made an isopropyl amide on one of my BOC groups (according to literature; amidation through carbamates). This correlates to my TLC analysis as I loose one oxygen then and it goes up. Because of time problems I did not isolate this product :-(
But now the really strange thing comes in. After all the starting compound has reacted, the electrophille is added. This gives one spot, much longer down the TLC plate. When I isolated the spot it turned out that the BOC and amide group is gone, and the electrophile have been attacked by the amine to yield a methyl carbamate. The bromine is unaffected. The last structure is validated by LC-MS, H-NMR and C-NMR, but I cant see how the amide + BOC can de deprotected by an electrophile. Maybe some intramolecular reactions? I Have never heard about deprotection of an pivatoyl group by a electrophile. I still have the MgCl as lewis acid, maybe it could do something on the other BOC group, but I am rather confused.
Any information regarding the mechanism, articles about this subject or ideas is more than welcome.
Thanks in advance.