135635-56-2Relevant academic research and scientific papers
Some transformations of tacrolimus, an immunosuppressive drug
Skytte, Dorthe M.,Jaroszewski, Jerzy W.,Johansen, Kenneth T.,Hansen, Steen Honore,Hansen, Liselotte,Nielsen, Peter G.,Frydenvang, Karla
, p. 514 - 522 (2013)
Transformations of the macrocyclic lactone tacrolimus (1), an important immunosuppressive drug produced by Streptomyces species, are described. These transformation products are primarily of interest as reference substances for drug impurity analyses. Upon action of acid (p-toluenesulfonic acid in toluene), tacrolimus is dehydrated by loss of water from the b-hydroxyketone moiety with partial inversion of configuration at C-8, resulting in formation of 5-deoxy-D5,6-tacrolimus and 5-deoxy-δ5,β-8-epitacrolimus. The structure of the latter was determined by single-crystal X-ray crystallography. The same products are formed upon action of free radicals (iodine in boiling toluene), along with formation of 8- epitacrolimus. The latter is converted by p-toluenesulfonic acid to 5-deoxy-D5,6-8-epitacrolimus. Treatment of tacrolimus with weak base (1,5-diazabicyclo[4.3.0]nonene) gives, in addition to 8-epitacrolimus, the open-chain acid corresponding to 5-deoxy-Δ5,β-tacrolimus, a rare non-cyclic derivative of tacrolimus. Strong base (t-butoxide) causes pronounced degradation of the molecule. Thermolysis of tacrolimus leads to ring expansion by an apparent [3,3]-sigmatropic rearrangement of the allylic ester moiety with subsequent loss of water from the b-hydroxyketone moiety. 1H and 13C NMR spectra of the obtained compounds, complicated by the presence of amide bond rotamers and ketal moiety tautomers, were assigned by extensive use of 2D NMR techniques.
Synthesis and characterization of an epimer of tacrolimus, an immunosuppressive drug
Skytte, Dorthe M.,Frydenvang, Karla,Hansen, Liselotte,Nielsen, Peter G.,Jaroszewski, Jerzy W.
experimental part, p. 776 - 779 (2010/07/13)
8-Epitacrolimus (2), a new l-pipecolic acid macrolide lactone, was obtained by base-catalyzed epimerization of tacrolimus (FK-506, 1), an important immunosuppressive drug, and its structure determined by a single-crystal X-ray diffraction method. The compound was fully characterized by spectroscopic techniques. The epimer is of importance due to its potential biological effects as well as because of its possible formation during formulation, handling, and use of tacrolimus products.
