Stereochemistry of a macrocyclic spermidine alkaloid from Caesalpinia digyna Rottl. X-Ray determination of the structure of caesalpinine C (celallocinnine)

Abstract

The molecular geometry of caesalpinine C (1)(celallocinnine), a macrocyclic spermidine alkaloid isolated from Caesalpinia digyna Rottl., has been determined by means of single-crystal X-ray analysis. The ¹H and ¹³C n.m.r. spectra could satisfactorily be interpreted on the basis of the X-ray structure. The compound, C₂₅H₃₁N₃O₂, is orthorhombic with space group P2₁2₁2₁ and lattice constants a= 9.963(2), b= 8.026(2), c= 28.627(5)Å, cell volume V= 2 289.1 ų, and Z= 4. Diffractometer intensity measurements were made with Cu-K_α radiation and least-squares adjustment of the atomic parameters converged to a final R value of 0.05.