A CONFORMATIONAL STUDY OF THE SEMISYNTHETIC ERGOT ALKALOID - TERGURIDE

Conformational analyses studied by 2D NMR techniques and X-ray diffrac tion methods are reported for the semisynthetic ergot alkaloid - tergu ride, in the form of free base and as the protonated species. The stru cture of terguride hydrogen maleate monohydrate (C20H29N4O)+(C4H3O4)-. H2O (II) was solved by direct methods and refined anisotropically to an R value of 0.068 for 1 991 unique observed reflections. The title c ompound crystallizes in the triclinic space group P1 with lattice para meters a = 7.061(2), b = 9.205(1), c = 12.223(4) angstrom, alpha = 96. 36(2), beta = 107.15(2), gamma = 106.67(1)-degrees. Studies revealed t hat terguride monohydrate (I) and its protonized form (terguride hydro gen maleate monohydrate) possesses the identical conformations both in solution and in the solid state - an envelope for C and a chair for D ergoline rings.