TY - JOUR
T1 - Some transformations of tacrolimus, an immunosuppressive drug
AU - Skytte, Dorthe Mondrup
AU - Jaroszewski, Jerzy W.
AU - Johansen, Kenneth
AU - Hansen, Steen Honore'
AU - Hansen, Liselotte
AU - G. Nielsen, Peter
AU - Frydenvang, Karla Andrea
PY - 2013/2/14
Y1 - 2013/2/14
N2 - 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.
AB - 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.
U2 - 10.1016/j.ejps.2012.12.001
DO - 10.1016/j.ejps.2012.12.001
M3 - Journal article
SN - 0928-0987
VL - 48
SP - 514
EP - 522
JO - European Journal of Pharmaceutical Sciences
JF - European Journal of Pharmaceutical Sciences
IS - 3
ER -