THE CRYSTAL AND ABSOLUTE MOLECULAR-STRUCTURE OF LOW-MELTING NICERGOLINE (FORM-II)

The absolute structure of nicergoline (C24H26BrN3O3) was solved by dir ect methods and refined anisotropically to the R value of 0.039 for 3 145 observed Friedel pairs. The title semisynthetic ergot alkaloid cry stallizes in the orthorhombic space group P2(1)2(1)2(1) with lattice p arameters a = 11.507(2) angstrom, b = 13.219(2) angstrom, c = 14.753(2 ) angstrom, Z = 4. The pyrrole moiety is nearly planar, the ergoline C ring has a half-boat conformation and the D ring is a regular chair. The absolute configuration has been found to be 5R, 8R and 10S.