Oligomerization Route to Py-Im Polyamide Macrocycles

Cyclic eight-ring pyrrole−imidazole polyamides are sequence-specific DNA-binding small molecules that are cell permeable and can regulate endogenous gene expression. Syntheses of cyclic polyamides have been achieved by solid-phase and solution-phase methods. A rapid solution-phase oligomerization approach to eight-ring symmetrical cyclic polyamides yields 12- and 16-membered macrocycles as well. A preference for DNA binding by the 8- and 16-membered oligomers was observed over the 12-ring macrocycle, which we attributed to a conformational constraint not present in the smaller and larger systems

Euphorbia factor L8: a diterpenoid from the seeds of Euphorbia lathyris

The title compound [systematic name: (2S*,3S*,4R*,5R*,9S*,11S*,15R*)-5,15-diacet­oxy-3-nicotino­yloxy-14-oxolathyra-6(17),12(E)-diene], C30H37NO7, was isolated from the seeds of Euphorbia lathyris. The tricyclic diterpenoid molecule contains an 11-membered ring, a five-membered ring exhibiting an envelope conformation and a three-membered ring. The 11-membered ring is cis-fused with the three-membered ring and trans-fused with the five-membered ring

2,4-Diamino-6-methyl-1,3,5-triazin-1-ium chloride

In the title compound, C4H8N5 +·Cl−, a two-dimensional layer packing network is observed in which every chloride anion links three adjacent 2,4-diamino-6-methyl-1,3,5-triazin-1-ium cations by N—H⋯Cl hydrogen-bonding inter­actions, forming 12-membered and eight-membered hydrogen-bonded rings with graph-set motifs R 4 4(12) and R 3 3(8), respectively. In addition, N—H⋯N hydrogen bonds are found between adjacent cations, forming another type of eight-membered [R 2 2(8)] hydrogen-bonded ring

N-[3-(4-Fluoro­benz­yl)-2,4-dioxo-1,3-diaza­spiro­[4.5]dec-8-yl]-2-methyl­benzene­sulfonamide

In the title compound, C22H24FN3O4S, the cyclo­hexane ring adopts a chair conformation and the five-membered ring is essentially planar, with a maximum deviation of 0.040 (2) Å. The dihedral angles between the five-membered ring and the tolyl and fluoro­benzene rings are 56.74 (12) and 89.88 (12)°, respectively. The two terminal benzene rings make a dihedral angle of 63.53 (12)°. The crystal structure displays inter­molecular C—H⋯O and N—H⋯O hydrogen bonds. An intra­molecular C—H⋯O hydrogen bond also occurs

An ortho­rhom­bic polymorph of 6-de­oxy-6-iodo-1,2:3,4-di-O-isopropyl­idene-α-d-galactopyran­oside

The title compound, C12H19IO5, is the ortho­rhom­bic polymorph of a previously reported monoclinic form [Krajewski et al. (1987 ▶). Bull. Pol. Acad. Sci. Chem. 35, 91–102]. The dihedral angles between the six-membered ring and the two five-membered rings are 67.66 (14) and 71.79 (13)°, whereas the dihedral angle between the five-membered rings is 74.41 (12)°, indicating that all three rings are twisted from each other. The six-membered ring has a twist-boat conformation while both of the five-membered rings have envelope conformations. The crystal structure is stabilized by a network of C—H⋯O contacts linking the mol­ecules into a two-dimensional array parallel to the ab plane

5,8-Dimethyl-3-methyl­ene-2-oxo-3,3a,4,5,5a,6,8a,8b-octa­hydro-2H-1-oxa-s-indacene-5-carbaldehyde

The title compound, C15H18O3, was synthesized from 9α-hy­droxy­parthenolide (9α-hy­droxy-4,8-dimethyl-12-methyl­ene-3,14-dioxatricyclo­[9.3.0.02,4]tetra­dec-7-en-13-one), which was isolated from the chloro­form extract of the aerial parts of Anvillea radiata. The five-membered lactone ring has a twisted conformation, while the six- and five-membered rings display chair and envelope conformations, respectively. The dihedral angle between the two five-membered rings is 50.57 (11)°

2,2,2-Trifluoro-1-[3-(2,2,2-trifluoro­acet­yl)azulen-1-yl]ethanone

There are two mol­ecules in the asymmetric unit of the title compound, C14H6F6O2, in which the azulene systems possess an almost planar geometry with maximum deviations of 0.0438 (15) and 0.0396 (14) Å. Besides intra- and inter­molecular C—H⋯O and C—H⋯F inter­actions, the structure displays three F⋯F contacts [2.793 (2), 2.8820 (17) and 2.9181 (16) Å]. Furthermore, a characteristic azulene π-stacking is observed with an alternating sequence of electron-rich five-membered rings and electron-deficient seven-membered rings [centroid–centroid distances = 3.5413 (12), 3.6847 (12), 3.5790 (12) and 3.7718 (12) Å]

Synthesis and Structural Properties of Novel Tricyclic 15-membered Azalides

Starting from 3-decladinosyl-9a,11-cyclic carbamates of 15 membered azalide, strained tricyclic aglycone derivatives were prepared. The bridging 5-membered hemiketal ring was obtained by intramolecular ketalization of intermediary 3-keto derivative, whereas 5-membered ether derivatives were obtained by intramolecular Williamson-type displacement. In case of 12-O-alkyl derivatives complete diastereoslective formation of ethers was observed, while unsubstituted compound gave diastereomeric mixture. NMR analysis was used to confirm the structures of new tricyclic azalide compounds.</p

(25R)-5a-Spiro­stane-3,12-dione

The title compound, C27H40O4, was obtained from the oxidation of (25R)-3b-hydr­oxy-5a-spiro­stan-12-one (Hecogenin) by Jone’s reagent. The mol­ecule contains six alicyclic and heterocyclic rings, all trans-fused, among which four six-membered rings adopt similar chair conformations while two five-membered rings assume an envelope conformation

N-{3-[2-(4-Fluoro­phen­oxy)eth­yl]-2,4-dioxo-1,3-diaza­spiro­[4.5]decan-7-yl}-4-meth­oxy­benzene­sulfonamide

In the title compound, C23H26FN3O6S, the two terminal aromatic rings form a dihedral angle of 49.26 (12)°. The cyclo­hexane ring adopts a chair conformation and the five-membered ring is essentially planar, with a maximum deviation from planarity of 0.0456 (19) Å. The dihedral angles between the five-membered ring and the meth­oxy­benzene and fluoro­benzene rings are 33.56 (11) and 81.94 (12)°, respectively. The crystal structure displays N—H⋯O hydrogen bonds as well as weak inter­molecular C—H⋯O inter­actions