Crystal structure of (+)-(1S,5S,6S,7S,10S,11S,16S)-16-hydroxy-7-(methoxymethoxy)-11,15,18,18-tetramethyl-3,13-dioxo-2,4-dioxatetracyclo[12.3.1.01,5.06,11]octadec-14-en-10-yl benzoate

In the fused tetracyclic system of the title compound, C29H36O9, the five-membered dioxolane ring adopts a twist conformation; the two adjacent C atoms deviate alternately from the mean plane of the other three atoms by −0.252 (6) and 0.340 (6) Å. The cyclohexane, cyclohexene and central cyclooctane rings show chair, half-chair and boat-chair forms, respectively. There are three intramolecular C—H...O interactions supporting the molecular conformation, with one S(6) and two S(7) graph-set motifs. In the crystal, intermolecular O—H...O hydrogen bonds connect the molecules into a helical chain running along the c-axis direction, generating a C(7) graph-set motif. The chains are further linked by intermolecular C—H...O interactions to construct a three-dimensional network. There is no valid C—H...π interaction.

Penicamide A, A Unique N,N′-Ketal Quinazolinone Alkaloid from Ascidian-Derived Fungus Penicillium sp. 4829

Previously unreported N,N′-ketal quinazolinone enantiomers [(−)-1 and (+)-1] and a new biogenetically related compound (2), along with six known compounds, 2-pyrovoylaminobenzamide (3), N-(2-hydroxypropanoyl)-2 amino benzoic acid amide (4), pseurotin A (5), niacinamide (6), citreohybridonol (7), citreohybridone C (8) were isolated from the ascidian-derived fungus Penicillium sp. 4829 in wheat solid-substrate medium culture. Their structures were elucidated by a combination of spectroscopic analyses (1D and 2D NMR and Electron Circular Dichroism data) and X-ray crystallography. The enantiomeric pair of 1 is the first example of naturally occurring N,N′-ketal quinazolinone possessing a unique tetracyclic system having 4-quinazolinone fused with tetrahydroisoquinoline moiety. The enantiomeric mixtures of 1 displayed an inhibitory effect on NO production in lipopolysaccharide-activated RAW264.7 cells, while the optically pure (–)-1 showed better inhibitory effect than (+)-1.

Unusual thermolysis of azacyclic allene under microwave conditions: crystal structure of (3RS,3aSR,8RS,8aRS)-methyl 5,6-dimethoxy-3a,10-dimethyl-1-phenyl-3,3a,8,8a-tetrahydro-3,8-(epiminomethano)cyclopenta[a]indene-2-carboxylate from synchrotron X-ray diffraction

The title compound, C25H27NO4(I), the product of the unusual thermolysis of azacyclic allene methyl 10,11-dimethoxy-3,8-dimethyl-6-phenyl-3-azabenzo[d]cyclodeca-4,6,7-triene-5-carboxylate, represents a bicyclic heterosystem and crystallizes in the monoclinic space groupP21/cwith three crystallographically independent molecules in the unit cell. These independent molecules adopt very similar geometries and differ only in the conformations of the two methoxy substituents on the benzene ring. In two of the three independent molecules, both methoxy groups are almost coplanar with the benzene ring [the C—C—O—Me torsion angles are 10.8 (2), 12.3 (2), 9.1 (2) and 13.6 (3)°], whereas in the third molecule, one of the methoxy groups is practically coplanar to and the other methoxy group is roughly perpendicular to the benzene ring, the C—C—O—Me torsion angles being 14.1 (2) and 76.5 (2)°. The molecule of (I) comprises a fused tetracyclic system containing two five-membered rings (cyclopentenes) and two six-membered rings (piperidine and benzene). The five-membered rings have the usual envelope conformation, with the methyl-subsituted C atom as the flap in each molecule, and the six-membered piperidine ring has a chair conformation. The methyl substituent at the N atom occupies the sterically favourable equatorial position. The carboxylate group lies almost within the basal plane of the parent cyclopentene ring [making dihedral angle of 11.68 (8), 18.94 (9) and 15.16 (9)° in the three independent molecules], while the phenyl substituent is twisted by 48.26 (6), 42.04 (6) and 41.28 (6)° (for the three independent molecules) relative to this plane. In the crystal, molecules of (I) form stacks along theb-axis direction. The molecules are arranged at van der Waals distances.

A new approach to alkaloid-like systems: synthesis and crystal structure of 1-(2-acetyl-11-methoxy-5,6-dihydro[1,3]dioxolo[4,5-g]pyrrolo[2,1-a]isoquinolin-1-yl)propan-2-one

The title compound, C19H19NO5, (I), is the product of a domino reaction between cotarnine chloride and acetylacetylene catalysed by copper(I) iodide. The molecule of (I) comprises a fused tetracyclic system containing two terminal five-membered rings (pyrrole and 1,3-dioxole) and two central six-membered rings (dihydropyridine and benzene). The five-membered 1,3-dioxole ring has an envelope conformation and the central six-membered dihydropyridine ring adopts a twist-boat conformation. The acyl substituent is almost coplanar with the pyrrole ring, whereas the methoxy substituent is twisted by 27.93 (16)° relative to the benzene ring. The 2-oxopropan-1-yl substituent is roughly perpendicular to the pyrrole ring. In the crystal, molecules are stacked along thea-axis direction; the stacks are linked by weak C—H...O hydrogen bonds into puckered layers lying parallel to (001).

Crystal structures of the two epimers from the unusual thermal C6-epimerization of 5-oxo-1,2,3,5,5a,6,7,9b-octahydro-7,9a-epoxypyrrolo[2,1-a]isoindole-6-carboxylic acid, 5a(RS),6(SR),7(RS),9a(SR),9b(SR) and 5a(RS),6(RS),7(RS),9a(SR),9b(SR)

The isomeric title compounds, C12H13NO4(Ia) and C12H13NO4(IIa), the products of an usual thermal C6-epimerization of 5-oxo-1,2,3,5,5a,6,7,9b-octahydro-7,9a-epoxypyrrolo[2,1-a]isoindole-6-carboxylic acid, represent the two different diastereomers and have very similar molecular geometries. The molecules of both compounds comprise a fused tetracyclic system containing four five-membered rings (pyrrolidine, pyrrolidinone, dihydrofuran and tetrahydrofuran), all of which adopt the usual envelope conformations. The dihedral angle between the basal planes of the pyrrolidine and pyrrolidinone rings are 14.3 (2) and 16.50 (11)°, respectively, for (Ia) and (IIa). The nitrogen atom has a slightly pyramidalized geometry [bond-angle sum = 355.9 and 355.3°, for (Ia) and (IIa)], respectively. In the crystal of (Ia), molecules form zigzag-like hydrogen-bonded chains along [010] through strong O—H...O hydrogen bonds and are further linked by weak C—H...O hydrogen bonds into complex two-tier layers parallel to (100). Unlike (Ia), the crystal of (IIa) contains centrosymmetric cyclic hydrogen-bonded dimers [graph setR22(14)], formed through strong O—H...O hydrogen bonds and are further linked by weak C—H...O hydrogen bonds into ribbons extending across [101].

Benzo[c]phenanthrene derivatives: Synthesis, optical properties and cytotoxic activity

A new benzo[c]phenanthrene ketone has been synthesized through Heck coupling and oxidative photocyclization. The optical properties of the target tetracyclic system were also investigated by UV-visible absorption and photoluminescence spectroscopy and an emission in the visible region was observed. The tetracyclic ketone has been reacted with primary amines in the presence of Lewis acid followed by NaBH4 reduction to provide new polyaromatic secondary amines in good yields and purity. All the synthesized new compounds were identified and characterized through a combination of nuclear magnetic resonance spectroscopy and mass spectrometric methods. The cytotoxic activity of all pure benzo[c]phenanthrene derivatives has been evaluated against Hep-2 cell line using (MTT) colori­metric assay.

Crystal structure of 26-(4-methylphenyl)-8,11,14,17-tetraoxa-28-azatetracyclo[22.3.1.02,7.018,23]hexacosa-2,4,6,18(23),19,21,24(1),25,27-nonaene

The title compound, C30H29NO4, is a tetracyclic system containing a 4-arylpyridine fragment, two benzene rings and an aza-17-crown-5 ether moiety, in a bowl-like arrangement. The pyridine ring is inclined to the 4-methylphenyl ring by 26.64 (6)°, and by 57.43 (6) and 56.81 (6)° to the benzene rings. The benzene rings are inclined to one another by 88.32 (6)°. In the crystal, molecules are linked by pairs of C—H...N hydrogen bonds, forming inversion dimers with anR22(14) ring motif. The dimers are linkedviaa number of C—H...π interactions, forming a three-dimensional architecture.

20-Nor-isopimarane cycloethers from the deep-sea sediment-derived fungus Aspergillus wentii SD-310

Five new 20-nor-isopimaranes, asperethers A–E (1–5), were isolated from the deep-sea derived fungus Aspergillus wentii SD-310. These compounds possess a unique 6/6/6/5 tetracyclic system and exhibited cytotoxicity against several tumor cell lines.