ABSTRACT
The title tetracyclic diterpenoid, 10,13,16,17-tetrahydroxy-9-methyl-15-oxo-20-norkaurane-18,10-carbolactone hemihydrate, C(20)H(28)O(6).0.5H(2)O, is a plant metabolite from Parinari sprucei, part of the Venezuelan Amazon flora. The asymmetric unit consists of two nearly identical molecules of the diterpenoid and one molecule of water. Some of the geometric parameters reflect steric strain in the molecule. The extended structure is characterized by hydrogen bonds and weaker hydrogen-mediated interactions, which involve all of the hydroxy groups and propagate in sheets that coincide with the (002) family of planes. The water molecule acts as a double hydrogen-bond donor and single acceptor and thus plays a critical role in the pattern of intermolecular interactions.
Subject(s)
Diterpenes/chemistry , Lactones/chemistry , Magnoliopsida/chemistry , Crystallography, X-Ray , Diterpenes, Kaurane , Hydrogen Bonding , Models, Molecular , Molecular Conformation , Molecular StructureABSTRACT
Androst-4-ene-3,17-dione (1) and 17alpha-methyltestosterone (2) are dimerized in the solid-state by UV radiation. These substances were selected by a search in the CSD among the steroid enones presenting in the crystalline state an intermolecular short contact between a hydrogen alpha to a carbonyl group and the oxygen of an enone system. Dimerization occurs by transfer of the hydrogen to the oxygen and connection between the two involved carbons. Androst-4-ene-3,17-dione (1) affords dimer 3 and trimer 4, both formed by connection of the C-16 of a molecule with the C-3 of a near one. Irradiation of 17alpha-methyltestosterone (2) gives the isomeric trienones 5 and 6. These compounds are reasonably formed by dehydration of unisolated intermediate products 7 and/or 8 obtained by coupling of two molecules through a linkage between the C-2 and the C-3' carbons. The formation mechanisms of the photoproducts are satisfactory explained on the basis of the molecular arrangement of the monomers in the crystal state. Modeling of the dimeric molecules was done using molecular mechanics calculations. A single-crystal X-ray of the dimer of androst-4-ene-3,17-dione confirms the structural interpretation of spectral data. The conformer found in the solid-state agrees well with the results of molecular mechanics calculations.
Subject(s)
Androstenedione/chemistry , Ketones/chemistry , Methyltestosterone/chemistry , Spectrophotometry, Ultraviolet/methods , Steroids/chemistry , Crystallography, X-Ray , Dimerization , Models, Molecular , Molecular Conformation , Molecular Structure , Photochemistry/methodsABSTRACT
In the title compound, C(27)H(39)IN(3)(+).I(-), the acridinium system shows the usual approximate mirror symmetry about the central C.N line, and the corresponding bond lengths and angles in the two halves agree within experimental error. The alkyl chain at the ring N atom is initially perpendicular to the ring plane and then bends sharply at the fourth C atom. Pairs of centrosymmetrically related cations overlap two of their rings and the dimethylamino groups are also partly involved in the overlap. Each I(-) ion is involved in short-range interactions with two cations. These interactions give rise to a 14-membered cyclic structure, which involves pairs of cations and anions across an inversion centre.
