Triterpenoide. XIX. 3β‐Hydroxy‐11‐oxo‐18α‐olean‐12‐en‐28‐säure‐methyl­ester und 3,11‐Dioxo‐18α‐olean‐12‐en‐28‐säure‐methyl­ester

The X‐ray crystal structure analyses of 3β‐hydroxy‐11‐oxo‐18α‐olean‐12‐en‐28‐oic acid methyl ester ethanol solvate, C₃₁H₄₈O₄·C₂H₆O, (I), and 3,11‐dioxo‐18α‐olean‐12‐en‐28‐oic acid methyl ester, C₃₁H₄₆O₄, (II), are described. These two compounds differ only in the structure of ring A. In (I), ring A has a chair conformation, while in (II), it has a twisted boat conformation. In both compounds, ring C has a slightly distorted sofa conformation, rings B, D and E are in chair conformations, and rings D and E are trans‐fused. The asymmetric unit of (I) contains one mol­ecule of ethanol linked by hydrogen bonds with two different mol­ecules of (I).     

3β‐Acetoxy‐5α,6β‐di­hydroxybisnorcholanic acid 2216 lactone

In the title compound, C₂₄H₃₆O₆, the ester linkage in ring A is equatorial. The six‐membered rings A, B and C have chair conformations. The five‐membered ring D adopts a 13β,14α‐half‐chair conformation and the E ring adopts an envelope conformation. The A/B, B/C and C/D ring junctions are trans, whereas the D/E junction is cis.     

Triterpenoide. XX. 3β‐Acetoxy‐12‐oxo‐18β‐olean‐ und 3β‐Acetoxy‐12,19‐dioxo‐9(11),13(18)‐oleandien‐28‐säure‐methyl­ester

The structures of methyl 3β‐acetoxy‐12‐oxo‐18β‐olean‐28‐oate [C₃₃H₅₂O₅, (I)] and methyl 3β‐acetoxy‐12,19‐dioxoolean‐9(11),13(18)‐dien‐28‐oate [C₃₃H₄₆O₆, (II)] are described. In (I), all rings are in the chair conformation, rings D and E are cis and the other rings trans‐fused. In compound (II), only rings A and E are in the chair conformation, ring B has a distorted chair conformation, ring C a distorted half‐boat and ring D an insignificantly distorted half‐chair conformation.     

24(R)‐Acetyl­oxy‐1α,2α‐epoxy­cholesta‐4,6‐dien‐3‐one hydrate

In the title compound, C₂₉H₄₂O₄·H₂O, cyclo­hexane rings A and B are in the sofa conformation, ring C is in a chair conformation and the five‐membered ring D is in an envelope conformation. The structure is stabilized by inter‐ and intramolecular C—H?O and O—H?O hydrogen bonds.     

20‐Hydroxy­imino‐5α‐pregna‐9(11),16‐dien‐3β‐yl acetate and 17‐oxo‐5α‐androst‐9(11)‐en‐3β‐yl acetate

In the title compounds, C₂₃H₃₃NO₃ and C₂₁H₃₀O₃, respectively, the ester linkage in ring A is equatorial. In these steroids, the six‐membered rings A and B have chair conformations, but ring C can be better described as a half‐chair. The five‐membered ring D adopts a 14α‐envelop conformation. The A/B, B/C and C/D ring junctions are trans.     

6β‐Hydroxy‐5β‐methyl‐20‐oxo‐19‐norpregn‐9(10)‐en‐3β‐yl acetate

In the title compound, C₂₃H₃₄O₄, which is an intermediate in the synthesis of pregnane derivatives with a modified skeleton that show potent abortion‐inducing activity, the conformation of ring B is close to half‐chair due to the presence of both the C=C double bond and the axial 5β‐methyl group. Rings A and C have conformations close to chair, while ring D has a twisted conformation around the bridgehead C—C bond. Molecules are hydrogen bonded via the hydroxyl and acetoxy groups into infinite chains. Quantum‐mechanical ab initio Roothan Hartree–Fock calculations show that crystal packing might be responsible for the low values of the angles between rings A and B, and between ring A and rings C and D, as well as for a different steric position of the methyl ketone side chain compared to the geometry of the free molecule.     

16‐[3‐Methoxy‐4‐(2‐piperidin‐1‐yl­ethoxy)­benzyl­idene]‐17‐oxoandrost‐5‐en‐3β‐yl acetate monohydrate

The title compound, C₃₆H₄₉NO₅·H₂O, has the outer two six‐membered rings of the steroid nucleus in chair conformations. The central ring B of the steroid nucleus is in an 8β,9α‐half‐chair conformation, while ring D of the steroid adopts a slightly distorted 13β,14α‐half‐chair conformation. The piperidine ring is in a chair conformation. The methoxy­benzyl­idene moiety has an E configuration with respect to the carbonyl group at position 17. Intermolecular O—H?O and O—H?N hydrogen bonds link the steroid and water mol­ecules into chains which run parallel to the b axis.     

A new estra‐1,3,5(10)‐triene‐3,17β‐diol solvate: estradiol–methanol–water (3/2/1)

The title solvate of the steroid 17β‐estradiol (E₂) with methanol and water, C₁₈H₂₄O₂·0.67CH₄O·0.33H₂O, is the first E₂ derivative to contain three crystallographically independent mol­ecules in the asymmetric unit. The three steroid mol­ecules, along with two methanol mol­ecules and a water mol­ecule, create a three‐dimensional hydrogen‐bonded system. Three‐sided columns are formed, with the estradiol mol­ecules aligned lengthwise parallel to (101), and joined by solvent mol­ecules at both hydro­philic ends. The three estradiol mol­ecules differ slightly in their ring‐bowing angles, i.e. the angle between the mean plane of the A ring and that of the BCD ring; this angle ranges from 7.1 to 12.2°.     

16‐(4‐Cyano­benzyl­idene)‐17‐oxo­androst‐5‐en‐3β‐ol

In the title compound, 4‐(3β‐hydroxy‐17‐oxoandrost‐5‐en‐16‐ylidenemethyl)benzonitrile, C₂₇H₃₁NO₂, rings A and C of the steroid nucleus are in chair conformations. The central six‐membered ring B is in an 8β,9α‐half‐chair conformation, while the five‐membered ring D adopts a 13β,14α‐half‐chair conformation. The cyano­benzyl­idene moiety has an E configuration with respect to the carbonyl group at position C17. The dihedral angle between the planes of the steroid nucleus and the cyano­benzyl­idene moiety is 22.61 (15)°. Intermolecular O—H⃛N hydrogen bonds formed between the hydroxyl group of the steroid and the N atom of the cyano­benzyl­idene moiety of symmetry‐related mol­ecules link the steroid mol­ecules into chains which run parallel to the b axis.     

17α,21‐Di­hydroxy‐16β‐methylpregna‐1,4‐diene‐3,11,20‐trione (meprednisone)

The title compound, C₂₂H₂₈O₅, is a commercial therapeutic agent of the steroid class. Both independent mol­ecules in the asymmetric unit have six‐membered A rings that are planar, while the B and C rings adopt normal chair conformations. The five‐membered D ring is in a 13β,14α‐half‐chair con­formation, and the B/C and C/D ring junctions are in trans positions. Cohesion in the crystal is provided by O—H⃛O hydrogen bonds, which generate chains of mol­ecules that are organized in a plane that lies along the crystallographic b axis.     

3β‐(1‐Allyl‐1‐pyrrolidinio)‐16‐(2‐pyridylmethylene)androst‐5‐en‐17β‐ol bromide hemihydrate

The title compound, C₃₂H₄₅N₂O⁺·Br^?·0.5H₂O, has the outer two six‐membered rings in chair conformations, while the central ring is in an 8β,9α‐half‐chair conformation. The five‐mem­bered ring of the steroid nucleus adopts a slightly deformed 14α‐envelope conformation. The pyridyl­methyl­ene moiety has an E configuration with respect to the hydroxyl group at position 17. The structure is stabilized by a network of O—H?Br‐type intermolecular hydrogen bonds.     

Solvatomorphism in (E)‐2‐(2,6‐dichloro‐4‐hydroxybenzylidene)hydrazinecarboximidamide

The structures of orthorhombic (E)‐4‐(2‐{[amino(iminio)methyl]amino}vinyl)‐3,5‐dichlorophenolate dihydrate, C₈H₈Cl₂N₄O·2H₂O, (I), triclinic (E)‐4‐(2‐{[amino(iminio)methyl]amino}vinyl)‐3,5‐dichlorophenolate methanol disolvate, C₈H₈Cl₂N₄O·2CH₄O, (II), and orthorhombic (E)‐amino[(2,6‐dichloro‐4‐hydroxystyryl)amino]methaniminium acetate, C₈H₉Cl₂N₄O⁺·C₂H₃O₂⁻, (III), all crystallize with one formula unit in the asymmetric unit, with the molecule in an E configuration and the phenol H atom transferred to the guanidine N atom. Although the molecules of the title compounds form extended chains via hydrogen bonding in all three forms, owing to the presence of different solvent molecules, those chains are connected differently in the individual forms. In (II), the molecules are all coplanar, while in (I) and (III), adjacent molecules are tilted relative to one another to varying degrees. Also, because of the variation in hydrogen‐bond‐formation ability of the solvents, the hydrogen‐bonding arrangements vary in the three forms.     

Hydrogen‐bonded networks in 5‐chloropyridin‐2‐amine–fumaric acid (2/1) and 2‐aminopyridinium dl‐malate

Crystals of 5‐chloropyridin‐2‐amine–(2E)‐but‐2‐enedioate (2/1), 2C₅H₅ClN₂·C₄H₄O₄, (I), and 2‐aminopyridinium dl ‐3‐carboxy‐2‐hydroxypropanoate, C₅H₇N₂⁺·C₄H₅O₅⁻, (II), are built from the neutral 5‐chloropyridin‐2‐amine molecule and fumaric acid in the case of (I) and from ring‐N‐protonated 2‐aminopyridinium cations and malate anions in (II). The fumaric acid molecule lies on an inversion centre. In (I), the neutral 5‐chloropyridin‐2‐amine and fumaric acid molecules interact via hydrogen bonds, forming two‐dimensional layers parallel to the (100) plane, whereas in (II), oppositely charged units interact via ionic and hydrogen bonds, forming a three‐dimensional network.     

(E)‐4‐[2‐(3,4,5‐Trimethoxyphenyl)ethenyl]nitrobenzene and its `bridge‐flipped' analogues

The solid‐state structures of three push–pull acceptor‐π‐donor (A‐π‐D) systems differing only in the nature of the π‐spacer have been determined. (E)‐1‐Nitro‐4‐[2‐(3,4,5‐trimethoxyphenyl)ethenyl]benzene, C₁₇H₁₇NO₅, (I), and its `bridge‐flipped' imine analogues, (E)‐3,4,5‐trimethoxy‐N‐(4‐nitrobenzylidene)aniline, C₁₆H₁₆N₂O₅, (II), and (E)‐4‐nitro‐N‐(3,4,5‐trimethoxybenzylidene)aniline, C₁₆H₁₆N₂O₅, (III), display different kinds of supramolecular networks, viz. corrugated planes, a herringbone pattern and a layered structure, respectively, all with zero overall dipole moments. Only (III) crystallizes in a noncentrosymmetric space group (P2₁2₁2₁) and is, therefore, a potential material for second‐harmonic generation (SHG).     

13,13a‐Di­hydro‐13‐methoxy‐9‐methyl‐1‐benzo­pyrano­[4,3‐i]­dinaphtho­[2,1‐c;1′,2′‐f]‐2,8‐dioxa­bicyclo­[3.3.1]­nonane

The crystal structure of the title compound, C₃₂H₂₄O₄, contains three fused di­hydro­pyran rings (A, B and C); ring A is fused with a benzene ring while the other two rings, B and C, are fused with naphthalene rings. Ring A adopts a half‐chair conformation with an equatorial methoxy group, whereas ring B assumes a distorted half‐chair conformation, the A/B ring junction being trans. Ring C adopts a distorted half‐boat conformation and is nearly orthogonal to ring B. Ring C is inclined to the best plane of ring A at an angle of 112.1 (1)°.     

9(R)‐[6(R)‐Hydroxy­methyl‐1‐oxa‐4‐thia­cyclo­hexan‐2‐yl]hypoxanthine–water (4/3), a nucleoside analogue

The title compound, 9(R)‐[6(R)‐hydroxy­methyl‐1‐oxa‐4‐thia­cyclo­hexan‐2‐yl]‐1,9‐di­hydro‐6H‐purin‐6‐one–water (4/3), C₁₀H₁₂N₄O₃S·0.75H₂O, crystallizes in the triclinic space group P1 with four mol­ecules in the asymmetric unit and 0.75 waters of hydration per mol­ecule. The structure was refined to an R value of 0.072 for 3382 observed reflections. The four crystallographically independent mol­ecules are designated A, B, C and D. All four oxa­thia­ne rings adopt the chair conformation and the purine bases are in an anti orientation with respect to the sugar moieties. Molecules A and D and mol­ecules C and B are base paired by a single hydrogen bond of the type N—H?N. These base pairs are again hydrogen bonded to their translated pairs in the direction of a cell diagonal.     

Racemic isopropyl 1,4‐dihydro‐2,6‐dimethyl‐4‐(6‐methyl‐2‐pyridyl)‐3‐nitropyridine‐5‐carboxylate hemi­benzene solvate

This analysis establishes the rotameric orientation of the pyridyl‐ring N atom of the title compound, C₁₇H₂₁N₃O₄·0.5C₆H₆, as antiperiplanar (ap) to the 1,4‐dihydropyridine H‐4, the absence of an intramolecular hydrogen bond between the 1,4‐dihydropyridine NH and the pyridyl‐N atom, and the unusual planarity of the 1,4‐dihydropyridine ring.     

6‐[3‐Hydroxy‐17‐oxoestra‐1,3,5(10)‐trien‐7β‐yl]­hexane­nitrile

In the title compound, C₂₄H₃₁NO₂, ring B adopts a conformation between the boat and twisted‐boat forms. This conformation best accommodates adverse intramolecular H⋯H interactions between the H atoms of the 7β‐substituent and the two nearest ring H atoms. The tilt angle between rings A and D is 28.6 (1)°.     

17‐Oxo‐16‐(2‐pyridyl­methyl­ene)­androst‐5‐en‐3β‐ol monohydrate

The title compound, C₂₅H₃₁NO₂·H₂O, has the outer two six‐membered rings in chair conformations, while the central ring is in an 8β,9α‐half‐chair conformation. The five‐membered ring adopts a 13,14‐half‐chair conformation. The pyridyl­methyl­ene moiety has an E configuration with respect to the carbonyl group at position 17. The structure is stabilized by intermolecular O—H?N and O—H?O hydrogen bonds.     

2,6‐Di­benzyl‐1,2,3,5,6,7‐hexa­hydro‐2,4,6,8‐tetra­aza‐s‐indacene and 2,6‐bis(4‐methoxy­benzyl)‐1,2,3,5,6,7‐hexa­hydro‐2,4,6,8‐tetra­aza‐s‐indacene

The title compounds, C₂₂H₂₂N₄ and C₂₄H₂₆N₄O₂ [alternative names: 2,6‐dibenzyl‐2,3,6,7‐tetrahydro‐1H,5H‐dipyrrolo[3,4‐b; 3′,4′‐e]pyrazine and 2,6‐bis(4‐methoxybenzyl)‐2,3,6,7‐tetrahydro‐1H,5H‐dipyrolo[3,4‐b;3′,4′‐e]pyrazine], two 1,2,3,5,6,7‐hexa­hydro‐2,4,6,8‐tetra­aza‐s‐indacene derivatives, are both centrosymmetric and have similar S‐shaped structures. In the former, there are two independent mol­ecules (A and B), both of which possess C_i symmetry. These two mol­ecules are arranged such that the benzene ring substituent of mol­ecule B is directed towards the plane of the benzene ring substituent of mol­ecule A, with a dihedral angle of 55.4 (2)° between their planes. The shortest C—H⋯C distance is, however, only 3.21 (1) Å. In both compounds, the benzene ring substituents are almost perpendicular to the plane of the central pyrazine ring, and the pyrrolidine rings have perfect envelope conformations. In the crystal structures of both compounds, the mol­ecules pack in a herring‐bone arrangement.