The hemisynthesis of the title compound, C22H32O2, was carried out through direct acetyl-ation reaction of the naturally occurring diterpene totarol [systematic name: (4bS,8aS)-4b,8,8-trimethyl-1-propan-2-yl-5,6,7,8a,9,10-hexa-hydro-phen-an-thren-2-ol]. The mol-ecule is built up from three fused six membered rings, one saturated and two unsaturated. The central unsaturated ring has a half-chair...

In the title dihalogenated trichodermin mol-ecule, C(17)H(24)Br(2)O(4) (systematic name: 9,10-dibromo-12,13-epoxy-trichothec-9-en-4β-yl acetate), the five-membered ring displays an envelope conformation, whereas the two six-membered rings show the same conformation, viz. chair. As for the seven-membered ring, the dihedral angle between the mean planes formed by the four C atoms of the envelope ...

The title compound, C(16)H(20)O(5), was synthesized from ilicic acid [2-(8-hy-droxy-4a,8-dimethyl-deca-hydro-naphthalen-2-yl)acrylic acid], which was isolated from the chloro-form extract of the aerial part of Inula viscose (L) Aiton [or Dittrichia viscosa- (L) Greuter]. The molecule is built up from two fused six-membered rings, the epoxidized six-membered ring adopts a half-chair conformation...

THE TITLE COMPOUND [SYSTEMATIC NAME: 2-(4a,8-dimethyl-1,2,3,4,4a,5,6,8a-octa-hydro-naphthalen-2-yl)acrylic acid anhydride], C(30)H(42)O(3), is a new isocostic anhydride which was synthesized from the aerial part of Inula Viscosa- (L) Aiton [or Dittrichia Viscosa- (L) Greuter]. The mol-ecule adopts an essentially linear shape with two terminal fused-rings bridged by the anhydride group. The exte...

The title compound, C16H22Br2Cl2, was synthesized from β-him-achalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The mol-ecule is built up from fused six- and seven-membered rings and an appended three-membered ring. The six-membered ring has a half-chair conformation, whereas the seven-...

Interconversion of carbon sites in boat-chair-boat (BCB) cyclodecane occurs by way of the twist-boat-chair (TBC) conformation, which predicts that C-1 exchanges with C-4, etc. The previously obtained low-temperature 13C spectra could be matched by assuming (1,4) or (1,3) exchange, but not (1,2) exchange. A free-energy barrier of 5.54 kcal/mol was obtained for conversion of BCB to TBC at -137.4 ...

The title mol-ecule (systematic name: 12-O-β-tigloyl-3β,14β-dihydroxy-pregn-5-en-20-one), C(26)H(38)O(5), isolated from aerial parts of Hoodia gordonii, has its steroid A and C rings in chair conformations, its B ring in a half-chair conformation, and its five-membered ring in an envelope conformation. The OH group at the C/D ring junction forms an intra-molecular hydrogen bond with the keto su...

In the crystal structure of the racemic title isoxazolidine, C(19)H(27)NO, the relative stereochemistry between the phenyl group and the bridgehead H atom is shown to be syn. There are two mol-ecules in the asymmetric unit, one of which is the 7R*,13R* enanti-omer, and one of which is the 7S*,13S* enanti-omer. These enanti-omers adopt different orientations of the phenyl ring with respect to th...

In the crystal structure of the title compound, C(26)H(33)N(3)O(4), there are two crystallographically independent mol-ecules. The two cyclohexane rings are trans-fused; the ring neighboring the phenyl group is in a half-chair conformation and the other is in a chair conformation. The two nitro groups and the benzene ring of the dinitro-phenyl group are almost coplanar. Intra-molecular N-H⋯O hy...

In the title compound, C(27)H(32)N(2)O(5), the morpholine ring adopts a chair conformation with two C atoms deviating by -0.656 (4) and 0.679 (3) Å from the least-squares plane defined by the rest of atoms in the ring. The tetra-hydro-pyridine ring adopts a half-chair conformation. The mol-ecular structure is stabilized by a strong intra-molecular O-H⋯O inter-action, generating an S(6) motif. T...