113304-79-3Relevant articles and documents
APPLICATION OF CINNAMYLOXYCARBONYL (Coc) PROTECTION DURING THE SYNTHESIS OF Coc-Pro-MePhe-MeAla-OMe. CHAIN RUPTURE OF THE TRIPEPTIDE ON CHROMATOGRAPHY.
Sharma, N.K.,Anteunis, M.J.O.
, p. 467 - 472 (2007/10/02)
The preparation of 1-(cinnamyloxycarbonyloxy)benztriazole (Coc-OBt), as reported in literature, results in a mixture of 50percent Coc-OBt (6) next to 13percent of 1-(cinnamyloxy)benztriazole (7).The reagent 6 is stable for several months in the fridge.Coc-protection of Pro can be obtained in an improved yield by a slightly modified procedure.Coc-Pro-MePhe-MeAla-OMe was prepared in good yields using BOP-Cl as the activator for coupling.In an attempt to isolate the tripeptide by chromatography on SiO2 we found it to decompose into Coc-Pro and the cyclic dipeptide (DKP) c(MePhe-MeAla).The same DKP is formed from the dipeptide ester salt Tfa.MePhe-MeAla-OMe on standing in CDCl3.These findings stress the ease of chain rupture of peptides caused by acidic agents when they possess a triad of N-alkylated amino acids (3).