A bunch of papers came out in the last year using trifluoroacetylacetone as a first step prior to ethyl or isobutyl chloroformate derivatization.
http://www.omicsonline.org/open-access/ ... 000248.pdf **this one even does arginine which is possible. Guanidino compounds condense with 2,4 diones to form pyrimidyl derivatives*
http://link.springer.com/article/10.100 ... 011-1957-yhttp://pubs.rsc.org/en/content/articlel ... c4ay03098bI have been trying to repeat their protocols with no success. I've tried different buffers and pH's altered the solvent ration more in line with other papers (their mix for the chloroformate derivatization is way high aqueous and low pyridine compared to others with no success. I can get chloroformate derivatives that I can identify especially when I match the chloroformate and alcohol (methyl chloroformate with methanol and ethyl chloroformate with ethanol). It is quite frustrating as they can use an FID and simple db-5 column and their chromatograms are beautiful.
I'm skeptical though. Acetylacetone reacts with primary amines so how do they get proline right in line with the others? Also why use ammonium acetate buffer when the reagents react with both primary amines and carboxylic acids. I tried phosphate instead. I wonder if they are simply getting methyl esters from the methanol/chloroformate and ethyl or isobutyl carbamates from the chloroformate rather than schiff base esters.
If anyone gets it to work let me know.