Collect. Czech. Chem. Commun. 1995, 60, 1333-1342

Absolute Crystal Structure Determination of Ergot Alkaloid - Dihydroergocristine Methanesulfonate Monohydrate

Jan Čejkaa, Jan Ondráčeka, Michal Hušáka, Bohumil Kratochvíla, Alexandr Jegorovb,* and Josef Stuchlíkc

a Department of Solid State Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
b Galena Co., Research Unit, Branišovská 31, 370 05 České Budějovice, Czech Republic
c Galena Co., R. & D., 747 70 Opava-Komárov, Czech Republic


Dihydroergocristine methanesulfonate monohydrate crystallizes in orthorhorhombic space group P21212 (No. 18) with Z = 4, a = 12.736(2) Å, b = 39.089(5) Å, c = 7.130(1) Å, V = 3549.6(9) Å3. The indole moiety is nearly planar, both the ergoline ring C and the tripeptide ring F addopt an envelope E6 conformation. The ergoline ring D and the tripeptide ring E have a chair 1C4 conformation. The conformation of the ring G is between E1 and 5T1. The benzene ring H is planar. The structure was solved by direct methods and refined anisotropically to the final R value of 0.078 for 4219 statistically significant observed reflections [I o 1.96s(I)]. The absolute chirality was determined based on anomalous dispersion as: C4 (R), C8 (R), C6 (R), C17 (R), C25 (S), C24 (S), C19 (S).