Premature removal of N(α)-9-fluorenylmethyloxycarbonyl in thermodynamically controlled enzymatic coupling trials

Article abstract of DOI:10.1016/S0040-4039(98)00786-2

Incubation of N(α)-Fmoc-ISDR-OH and amino components in mixtures of N,N-dimethylformamide/1,1,1,3,3,3-hexafluoroisopropanol (DMF/HFIP), DMF/2,2,2-trifluoroethanol (TFE) or DMF/1,4-butanediol (BD), 0.2M Tris/HCl buffer, triethylamine (TEA) and apparent pH range 8.0-8.9, led to the undesired formation of variable amounts of dibenzofulvene in the reaction media. Such side reaction, which resulted from a premature Fmoc removal, is minimised by the use 1M buffer or by the increment of the trifluoroethanol proportion in the mixtures.