Oxidation of cyclic ene-carbamates with Oxone

Cyclic ene-carbamates, from 4-membered to 8-membered, were submitted to metal-catalyst-free oxidation using Oxone, a stable and nonpollutant oxidizing reagent. The reaction resulted in the carbon-carbon double bond cleavage to give the corresponding N-formyl-w-amino acids with the exception of the 4-membered cyclic ene-carbamate that was creaved at the N-C(1) bond affording ss-alanine instead of N-formylglycine. Enantiomeric 5-membered cyclic ene-carbamates having an ester function a-positioned to nitrogen were instead oxidized to pyroglutamic esters without racemization. The outcome of the Oxone oxidation of cyclic ene-carbamates is discussed and compared with those previously reported of the same substrates oxidized with RuO4 and the corresponding cyclic 3-azaketones oxidized with Oxone. Boc NHCOOH Boc Oxone N Ozone Boc NCHOCOOH Boc N Boc N Oxonen = 1 – 4 Boc NCHOHOOO-n ELOOC Oxone EtOOC n = 1 – 4 N