I am trying to synthesize N-Protected Beta-Amino Ketones via mannich reaction. I tried to synthesize it using many reagents such as Sulfamic acid, Molecular Iodine, l-Prolin, PTSA etc., but I could not succeed. The products with CBZ protected Beta-Amino Ketone have been reported with some of the catalysts I mentioned above. The only thing I am changing is tert-Butyl carbamate instead of Benzyl carbamate.
The reaction condition I use are:
1 mmol benzaldehyde, 1 mmol acetophenone, 1 mmol tert-Butyl carbamate and 10 mol% catalyst and stirring them at RT. I tried these reactions for 48 hours but I could not get the desired products. What should I do to complete the reaction? Am I going wrong with the reaction?
Please help, the scheme is attached here.
Hi. I think your boc-amine will not be nucleophilic enough. You should try with benzyl amine or other functional wich will allow the free pair of nitrogen electons to be nucleophylic
I think any carbamate will be problematic or any other strong electron removing protecting group
Dear Sir,
Thank you very much for your valuable suggestions. In the paper attached here they have done the same reaction with NH2CBZ with I2. In my case it is it is only NH2BOC. Can you suggest some routes to synthesize the same as it is easy to remove the Boc from the substrate?
Thanks Regards
may be these links could help you, just try with the boc imine
http://www.sciencedirect.com/science/article/pii/S004040399801661X#
http://www.orgsyn.org/orgsyn/prep.asp?prep=v86p0011
good luck
Catalyze your Mannich reaction by action of CeCl3 . 7H2O dopped by NaI – use this system directly or support this on silica gel or use Ce(III) supported on a weak acid cation-exchanger of a polyacrylate macroporous kind, ideally (preparations and synthetic application of such supported catalysts are described in patent CZ 2011/0799 (A3), Pazdera P. et al.).
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