1993 Volume 46 Issue 7 Pages 1149-1155
Tautomeric phenomenon was observed in the HPLC chromatogram obtained from a novel potent immunosuppressant, FK506, in ethanol solution. Two tautomeric compounds derived from FK506 were isolated and purified by HPLC. Their structures were elucidated by spectral analyses. The mechanisms for this tautomerization were also established based on the results of structure analysis.