Crystal and molecular structure of acanthothamine monohydrate-methanol: A new alkaloid from Acanthothamnus aphyllus

Abstract

C₃₄H₄₃O₁₆N·CH₃OH·H₂O is monoclinic,C ²₂ -P2₁. Unit cell dimensions at 293 K area=9.159(3),b=17.017(5),c=13.675(5) Å,β=109.49(2)°,V=2009(1) ų,D _c =1.28 g cm⁻³, andZ=2. The structure has been determined from single-crystal data collected with a four-circle diffractometer and refined from 2367 reflections down toR=0.064 andωR=0.082. The structural features determined from chemical and spectroscopic studies are confirmed and extended. The absolute configuration was determined by comparison with known absolute stereochemistry of the bromoacetylneoevonine monohydrate. The acanthothamine molecule is an evonine and neoevonine analogue showing an epimeric configuration at C(17) of the evoninic acid residue. The A and B rings adopt chair conformations. The C ring has a half-chair conformation. The crystal structure is stabilized by a three-dimensional network of hydrogen bonds and a number of intramolecular C-H⋯O and C-H⋯N interactions.