Mixed carboxylic‐carbonic acid anhydrides of acylamino acids and peptides as a convenient source of 2,4‐dialkyl‐5(4 H)‐oxazolones

• Published in: International Journal of Peptide and Protein Research
• Main Authors: CHEN, FRANCIS M.F., SLEBIODA, MAREK, BENOITON, N. LEO
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1988
• Subjects: Carbonic acid
• Online Access: http://dx.doi.org/10.1111/j.1399-3011.1988.tb00042.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1399-3011.1988.tb00042.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1399-3011.1988.tb00042.x

Racemic 2‐R 1 ‐4‐R 2 ‐5(4 H )‐oxazolones (R 1 = CH 3 , C 6 H 5 , C 6 H 5 CH 2 OCONHCH 2 R 2 = aliphatic and C 6 H 5 CH 2 ) have been prepared in good yields by reaction of the parent N ‐acetyl‐, N ‐benzoyl‐, and N ‐benzyloxycarbonylglycyl‐amino acids with methyl chloroformate in cold dichloromethane in the presence of N ‐methylmorpholine, followed by washing the mixtures with aqueous solutions and removal of the solvent. The products derived from optically active substrates contained enantiometric excesses of 83–98%. The method cannot be applied to the preparation of oxazolones from N ‐formylamino acids.