The structure of ergot alkaloid hydroxyergotamine
The structure of natural alkaloid hydroxyergotamine (P212121, a = 11.242(1) Å, b = 13.006(2) Å, c = 22.208(2) Å, Z = 4) has been solved by direct methods and refined anisotropically to the R value of 0.041. It has been established that the absolute stereochemistry classifies the alkaloid among the members of d-lysergic acid series. Ergolene moiety possesses the usual flap down conformation of the D ring. The piperazine ring F is in envelope form with the benzyl substituent in the eclipsed conformation. The L-proline ring has a predominant envelope form. The observed extended conformation of LSD-amide bond is stabilized by N3-NH3 ... O1 and O5-HO5 ... O1 intramolecular hydrogen bonds.