Conformational analyses are presented of several pharmacologically important norditerpenoid alkaloids (NDAs), in crystal and solution states. Crystal data 8 NDAs (4 free bases 4 salts) were obtained, which crassicauline A, aconitine HCl, methyllycaconitine HClO4 reported for the first time. 1D/2D NMR spectroscopies 7 (5 2 recorded comprehensively. conformations described with a revised cyclohex...

The efficient synthesis of a tetradentate diol-bispidine-based ligand and its metal complex with Zn(II) is here reported. single-crystal X-ray diffraction (SC-XRD) analysis the allowed characterization coordination sphere around cation as distorted square pyramid confirmed that bispidine core was in chair-chair (cc) conformation. This finding agreed theoretical analysis. structural data demonst...

The title compound, C30H48O2, contains a fused four-ring triterpenoid system. In the mol-ecule, the two cyclo-hexane rings adopt a chair conformation and a twist boat conformation, respectively, the central cyclo-hexene ring adopts a half-chair conformation whereas the five membered ring adopts an envelope conformation. In the crystal, O-H⋯O hydrogen bonds between the hy-droxy and carbonyl grou...

The title compound, C25H33BrN2O4, was synthesized from 9α-hy-droxy-parthenolide (9α-hy-droxy-4,8-dimethyl-12-methylen-3,14-dioxa-tri-cyclo-[9.3.0.0(2,4)]tetra-dec-7-en-13-one), which was isolated from the chloro-form extract of the aerial parts of Anvillea radiata. The mol-ecule is built up from two fused five- and ten-membered rings with an additional ep-oxy ring system and a bromo-phenyl-pipe...

ab initio calculations at hf/6-31g* level of theory for geometry optimization and mp2/6-31g*//hf/6-31g* for a single point total energy calculation are reported for the importantenergy-minimum conformations and transition-state geometries of 1, 3-diazacyclohepta-1, 2-diene (2) and 1, 3-diazacycloocta-1, 2-diene (3). the c2 symmetric twist-chair (2-tc)conformation of 2 is calculated to be 7.4 kj...

In the title compound, C39H58O4, the steroid rings A and C adopt a chair conformation, while ring B adopts a half-chair conformation, and ring D has an envelope conformation, with the methyl-substituted C atom as the flap. In the crystal, mol-ecules pack within layers parallel to (100), with their long axis parallel to the [101] direction. Adjacent layers are linked via C-H⋯O hydrogen bonds and...

In the title thienopyridine derivative, C(20)H(25)N(3)O(3)S(2), the piperazine ring exhibits a chair conformation and the tetra-hydro-pyridine ring exhibits a half-chair conformation. The folded conformation of the mol-ecule is defined by the N-C-C-N torsion angle of -70.20 (2) °. Inter-molecular C-H⋯S and C-H⋯O hydrogen bonds help to establish the packing.

The title compound, C(21)H(25)ClO, was semi-synthesized from isocostic acid, isolated from the aerial part of Inula Viscosa- (L) Aiton [or Dittrichia Viscosa- (L) Greuter]. The cyclo-hexene ring has a half-chair conformation, whereas the cyclo-hexane ring displays a chair conformation.

The title compound, C(19)H(26)O(4), was biotransformed from androstenedione. In the crystal, inter-molecular O-H⋯O hydrogen bonds link molecules into a corrugated sheet, which lies parallel to the ab plane. Ring A has a slightly distorted half-chair conformation, rings B and C adopt chair conformations, while the cyclo-pentane ring D adopts a 14α-envelope conformation.