16‐(4‐Iso­propyl­benzyl­idene)­androst‐4‐ene‐3,17‐dione

In the title compound, C₂₉H₃₆O₂, the outer cyclohexene ring of the steroid nucleus has a conformation that lies about half‐way between a half‐chair and an envelope, while the central and outer cyclo­hexane rings of the steroid nucleus have slightly distorted chair conformations. The steroidal cyclo­pentane ring adopts a 13β,14α‐half‐chair conformation. The benzyl­idene moiety has an E configuration with respect to the carbonyl group on the cyclo­pentane ring. The dihedral angle between the mean planes of the steroid nucleus and the benzyl­idene moiety is 35.54 (9)°. The packing of the mol­ecules is assumed to be dictated mainly by weak intermolecular C—H⋯O interactions.     

2,2′‐Methyl­enebis(3‐hydroxy‐2‐cyclo­hexen‐1‐one)

In the title compound, C₁₃H₁₆O₄, the cyclo­hexene rings adopt a sofa conformation. Adjacent mol­ecules are connected by C—H?O intermolecular interactions. Each mol­ecule is characterized by O—H?O intramolecular hydrogen bonds. The anti arrangement of the enolic OH group and the carbonyl O atom in the solid state is similar to the anti arrangement of the NH and carbonyl groups in indigo.     

3′,4′‐Bis(4‐chloro­phenyl)­spiro­[chroman‐3,5′(4′H)‐isoxazol]‐4‐one

The title compound, C₂₃H₁₅Cl₂NO₃, crystallizes with two independent mol­ecules in the asymmetric unit. The chroman­one moiety consists of a benzene ring fused with a six‐membered heterocyclic ring which adopts a sofa conformation. The five‐membered spiro­isoxazoline ring is in an envelope conformation. The p‐chloro­phenyl rings bridged by the five‐membered ring are nearly perpendicular to each other. The chromanone moiety of one mol­ecule packs into the cavity formed by the p‐chloro­phenyl rings of a second mol­ecule through the formation of C—H?π interactions. The structure is stabilized by weak C—H?O, C—H?Cl and C—H?π interactions.     

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.     

(1SR,2RS,5RS,6SR,8RS)‐7,7‐Dimethyltricyclo[6.2.1.01,6]undecane‐2,5,6‐triol: a supramolecular framework built from O—H⋯O hydrogen bonds

In the title compound, C₁₃H₂₂O₃, the asymmetric unit has two independent mol­ecules linked by a strong O—H?O hydrogen bond. The cyclo­hexane ring is trans fused to the cyclo­pentane ring bridged through an ethyl moiety. The hydroxyl groups act as donors as well as acceptors, resulting in an extensive two‐dimensional hydrogen‐bonded network in the (011) plane. Intermolecular O—H?O bonds between centrosymmetrically related mol­ecules form a four‐membered supramolecular assembly, leading to infinite chains parallel to the [01] direction, crosslinked in the [100] direction.     

4‐Ethynyl‐4‐hydroxycyclohexan‐1‐one and 4‐ethynyl‐4‐hydroxy‐2,3,5,6‐tetramethylcyclohexa‐2,5‐dien‐1‐one

The title compounds, C₈H₁₀O₂, (I), and C₁₂H₁₄O₂, (II), occurred as by‐products in the controlled synthesis of a series of bis­(gem‐alkynols), prepared as part of an extensive study of synthon formation in simple gem‐alkynol derivatives. The two 4‐(gem‐alkynol)‐1‐ones crystallize in space group P2₁/c, (I) with Z′ = 1 and (II) with Z′ = 2. Both structures are dominated by O—H?O=C hydrogen bonds, which form simple chains in the cyclo­hexane derivative, (I), and centrosymmetric dimers, of both symmetry‐independent mol­ecules, in the cyclo­hexa‐2,5‐diene, (II). These strong synthons are further stabilized by C[triple‐bond]C—H?O=C, C_methylene—H?O(H) and C_methyl—H?O(H) interactions. The direct intermolecular interactions between donors and acceptors in the gem‐alkynol group, which characterize the bis­(gem‐alkynol) analogues of (I) and (II), are not present in the ketone derivatives studied here.     

1,4‐Methano‐11a‐methyl‐4,4a,11,11a‐tetrahydro‐1H‐benzo­[b]­fluoren‐11‐one

The title compound, C₁₉H₁₆O, crystallizes with two mol­ecules of opposite chirality in the asymmetric unit. In both mol­ecules, the naphthalene and cyclo­pentanone moieties are individually planar. The two cyclo­pentane rings adopt envelope conformations, while the cyclo­hexane ring adopts a boat conformation.     

tert‐Butyl (3S,6R,9R)‐(5‐oxo‐3‐{[1(R)‐phenyl­ethyl]­carbamoyl}‐1,2,3,5,6,7,8,8a‐octa­hydro­indolizin‐6‐yl)­carbamate monohydrate at 95 K

The asymmetric unit of the title compound, C₂₂H₃₁N₃O₄·H₂O, incorporates one water mol­ecule, which is hydrogen bonded to the 3‐oxo O atom of the indolizidinone system. The two rings of the peptidomimetic mol­ecule are trans‐fused, with the six‐membered ring having a slightly distorted half‐chair conformation and the five‐membered ring having a perfect envelope conformation. The structure is stabilized by intermolecular O—H?O interactions between the water and adjacent peptide mol­ecules, and by N—H?O interactions between the peptide mol­ecules, which link the mol­ecules into infinite chains.     

3‐(p‐Chloro­phenyl)‐4‐phenyl‐4,5‐di­hydro­isoxazole‐5‐spiro‐2′‐1′,2′,3′,4′‐tetra­hydro­naphthalen‐1′‐one

In the title compound, C₂₄H₁₈ClNO₂, the phenyl ring and the tetralone moiety are approximately orthogonal to the isoxazoline ring. The isoxazoline ring adopts an envelope conformation, while the cyclo­hexenone ring of the tetralone moiety has an intermediate sofa/half‐chair conformation. In this structure, one C—H?N intermolecular and two C—H?O intramolecular hydrogen bonds occur; the H?A distances are 2.60, and 2.35 and 2.57 Å, respectively. The mol­ecules are held together by an intermolecular C—H?N hydrogen bond, forming a one‐dimensional chain along the [100] direction.     

4,5,9,10‐Tetrahydro‐4‐methyl‐2‐phenyl‐9,10‐epoxy‐3H,10aH‐cyclobuta[a]benzo[2,3,4‐de]isoquinoline‐3,5‐dione

In the title compound, C₂₁H₁₅NO₃, which is one of the photoreaction products of N‐methyl‐1,8‐naphthalene­dicar­box­imide with phenyl­acetyl­ene, the cyclo­butene and epoxy rings are trans to each other across the cyclo­hexene ring of the tetralin moiety. The dihedral angle between the mean planes of the cyclo­butene and cyclo­hexene rings is 112.80 (2)°, while the latter makes a dihedral angle of 103.70 (9)° with the epoxy ring. The crystal structure is stabilized by C—H⋯O intermolecular interactions.     

6‐Amino‐5,5,7‐tri­cyano‐3,3a,4,5‐tetra­hydro‐2H‐indene‐4‐spiro­cyclo­pentane

The positions of the C=C double bonds in the title compound, C₁₆H₁₆N₄, the subject of some dispute in the literature, have been clearly identified. The cyclo­hexene ring has a distorted half‐chair conformation and the cyclo­pentene and cyclo­pentane rings adopt envelope conformations. The dihedral angles between planar fragments of the cyclo­hexene and cyclo­pentene rings and of the cyclo­hexene and cyclo­pentane rings are 7.5 (1) and 86.98 (9)°, respectively. In the crystal, intermolecular N—H?N hydrogen bonds link the mol­ecules into infinite chains running in the [10] direction.     

3,4‐Di­hydro‐6‐methyl‐3‐β‐d‐ribo­furan­osyl‐4,5′‐cyclo‐9H‐imidazo[1,2‐a]­purin‐9‐one hydrate

In the title compound, C₁₃H₁₃N₅O₄·H₂O (4,5′‐cyclo­wyosine·H₂O), the cyclization forces a syn arrangement of the aglycon with respect to the sugar moiety. The ribo­furan­ose part of the mol­ecule displays a β‐d configuration with an envelope C1′‐endo pucker. The mol­ecules are arranged in columns along the short a axis and are linked to water mol­ecules through O—H?O and O—H?N hydrogen bonds.     

16‐Cyano‐13α‐(5‐methyl‐1,3,4‐oxa­diazol‐2‐yl)‐13,16‐seco‐17‐nor­androst‐5‐en‐3β‐yl acetate

In the title compound, C₂₃H₃₁N₃O₃, the outer cyclo­hexane rings have chair conformations, while the central cyclohexene ring adopts a half‐chair conformation. In the solid state, intra‐ and intermolecular C—H⋯N interactions are observed.     

Precursor of a β‐lactamase inhibitor: allyl (4S,8S,9R)‐10‐[(E)‐ethyl­idene]‐4‐methoxy‐11‐oxo‐1‐aza­tri­cyclo­[7.2.0.03,8]­undec‐2‐ene‐2‐carboxyl­ate

The molecular structure of the title tricyclic compound, C₁₇H₂₁NO₄, which is the immediate precursor of a potent synthetic inhibitor {Lek157: sodium (8S,9R)‐10‐[(E)‐ethyl­idene]‐4‐methoxy‐11‐oxo‐1‐aza­tri­cyclo­[7.2.0.0^3,8]­undec‐2‐ene‐2‐carboxyl­ate} with remarkable potency, provides experimental evidence for the previously modelled relative position of the fused cyclo­hexyl ring and the carbonyl group of the β‐lactam ring, which takes part in the formation of the initial tetrahedral acyl–enzyme complex. In this hydro­phobic mol­ecule, the overall geometry is influenced by C—H?O intramolecular hydrogen bonds [3.046 (4) and 3.538 (6) Å, with corresponding normalized H?O distances of 2.30 and 2.46 Å], whereas the mol­ecules are interconnected through intermolecular C—H?O hydrogen bonds [3.335 (4)–3.575 (5) Å].     

(Benzo­furan‐2‐yl)(3‐methyl‐3‐phenyl­cyclo­butyl)­methanone

The structure of the title compound, C₂₀H₁₈O₂, consists of a dimeric arrangement of benzo­furan mol­ecules around an inversion centre, linked via C—H⋯O hydrogen bonds. There are also C—H⋯π ring interactions. All these interactions result in the formation of infinite chains parallel to the [100] axis. The cyclo­butane ring is puckered, with a dihedral angle of 29.03 (13)° between the two three‐atom planes.     

2‐(Phenyl­amino­methyl­idene)­cyclo­hexane‐1,3‐dione

In the title compound, C₁₃H₁₃NO₂, there is polarization of π‐electron density from the amine N atom to the acceptor carbonyl groups: as a result, the mol­ecule exists predominantly in an azomethino‐1,3‐diketone tautomeric form. There is crystallographic evidence that the phenyl ring, although roughly coplanar with the rest of the mol­ecule, is deconjugated with the adjacent π system of the mol­ecule. The cyclo­hexane ring adopts an unsymmetrical half‐chair conformation and converts between two inversion‐related conformers. The mol­ecule is stabilized by an intramolecular hydrogen bond, while the intermolecular packing is dominated by a number of short C—H⋯O contacts.     

1‐Methyl‐1‐phenyl‐3‐[1‐hydroxy­imino‐2‐(succinimido)­ethyl]­cyclo­butane

In the title compound, C₁₇H₂₀N₂O₃, the cyclo­butane ring is puckered, with a dihedral angle of 19.11 (15)°. The 1‐phenyl and 3‐[1‐hydroxy­imino‐2‐(succinimido)­ethyl] groups are in cis positions. The mol­ecules are linked by O—H⋯O and C—H⋯π(benzene) interactions, forming a two‐dimensional network.     

Hydro­gen‐bonding patterns in cis‐4‐ammonio­cyclo­hexane­carboxyl­ate hemihydrate

In the title compound, C₇H₁₃NO₂·0.5H₂O, cis‐4‐amino­cyclo­hexane­carboxylic acid exists as a zwitterion and co‐crystallizes with water mol­ecules in a 2:1 amino acid–water ratio. The cyclo­hexane ring adopts a chair conformation, with the carboxyl­ate and ammonium groups in axial and equatorial positions, respectively. The basic motif in the crystal structure is a sandwich structure, formed by two amino acid units linked by head‐to‐tail hydrogen bonds. Hydro­gen bonds of the type N⁺—H⋯O—C—O⁻ link these motifs, forming helicoidally extended chains running along the c axis. The water molecule lies on a twofold axis and interacts with the chains by means of O—H⋯O hydrogen bonds.     

A second triclinic modification of 2′,6′‐di­methoxy­flavone

Crystals of a second triclinic modification of the title compound, 2‐(2,6‐di­methoxy­phenyl)‐4H‐1‐benzo­pyran‐4‐one, C₁₇H₁₄O₄, were grown from a hot cyclo­hexane solution. In the mol­ecule, the O—C—C—C torsion angle at the junction between the benzo­pyran and phenyl rings is 67.6 (3)°.     

2,6‐Di­phenylthiapyran‐4‐one

In the title compound, 2,6‐di­phenyl­thia­cyclo­hexan‐4‐one, C₁₇H₁₆OS, mirror site symmetry is retained by the mol­ecule in the solid state in the absence of C—H?X hydrogen bonds. The crystal structure is stabilized by van der Waals interactions, the shortest S?O and C?O contacts being 3.567 (2) and 3.512 (3) Å, respectively.