The sesquiterpenoid nootkatone and the absolute configuration of a di­bromo derivative

Nootkatone, or (4R,4aS,6R)‐4,4a,5,6,7,8‐hexa­hydro‐4,4a‐di­methyl‐6‐(1‐methyl­ethenyl)­naphthalen‐2(3H)‐one, C₁₅H₂₂O, a sesquiterpene with strong repellent properties against Formosan subterranean termites and other insects, has the valencene skeleton. The di­bromo derivative (1S,3R,4S,4aS,6R,8aR)‐1,3‐di­bromo‐6‐iso­propyl‐4,4a‐di­methyl‐1,2,3,4,5,6,7,8‐octa­hydro­naphthalen‐2‐one, C₁₅H₂₄Br₂O, has two independent mol­ecules in the asymmetric unit, which differ in the rotation of the iso­propyl group with respect to the main skeleton. The C—Br distances are in the range 1.950 (4)–1.960 (4) Å. Both independent molecules form zigzag chains, with very short intermolecular carbonyl–carbonyl interactions, having the perpendicular motif and O⋯C distances of 2.886 (6) and 2.898 (6) Å. These chains are flanked by intermolecular Br⋯Br interactions of distances in the range 4.067 (1)–4.218 (1) Å. The absolute configuration of the di­bromo derivative was determined, from which that of nootkatone was inferred.     

A new photochromic tetra­hydro­indolizine

The title compound, di­methyl 10b′‐(4‐fluoro­styryl)‐8′,9′‐di­methoxy‐4‐nitro‐5′,6′‐di­hydrospiro­[9H‐fluorene‐9,1′(10b′H)‐pyrrolo­[2,1‐a]­iso­quinoline]‐2′,3′‐di­carboxyl­ate, C₃₈H₃₁FN₂O₈, is a new photochromic tetra­hydro­indolizine. One of the C—C bonds at the spiro C atom is very long [1.630 (2) Å], thus explaining the photochromic behaviour.     

tert‐Butyl (6S)‐4‐hydroxy‐6‐isobutyl‐2‐oxo‐1,2,5,6‐tetra­hydropyridine‐1‐carboxyl­ate and tert‐butyl (4R,6S)‐4‐hydroxy‐6‐iso­butyl‐2‐oxopiperidine‐1‐carboxyl­ate

X‐ray studies reveal that tert‐butyl (6S)‐6‐iso­butyl‐2,4‐dioxo­piperidine‐1‐carboxyl­ate occurs in the 4‐enol form, viz. tert‐butyl (6S)‐4‐hydroxy‐6‐iso­butyl‐2‐oxo‐1,2,5,6‐tetra­hydropyri­dine‐1‐carboxyl­ate, C₁₄H₂₃NO₄, when crystals are grown from a mixture of di­chloro­methane and pentane, and has an axial orientation of the iso­butyl side chain at the 6‐position of the piperidine ring. Reduction of the keto functionality leads predominantly to the corresponding β‐hydroxy­lated δ‐lactam, tert‐butyl (4R,6S)‐4‐hydroxy‐6‐iso­butyl‐2‐oxo­piperidine‐1‐car­boxyl­ate, C₁₄H₂₅NO₄, with a cis configuration of the 4‐hydroxy and 6‐iso­butyl groups. The two compounds show similar molecular packing driven by strong O—H⋯O=C hydrogen bonds, leading to infinite chains in the crystal structure.     

Simvastatin

Simvastatin, or (1S,3R,7S,8S,8aR)‐8‐{2‐[(2R,4R)‐4‐hydroxy‐6‐oxo‐3,4,5,6‐tetra­hydro‐2H‐pyran‐2‐yl]­ethyl}‐3,7‐di­methyl‐1,2,3,7,8,8a‐hexa­hydro­naphthalen‐1‐yl 2,2‐di­methyl­butan­oate, C₂₅H₃₈O₅, is almost isostructural with lovastatin, and the general conformational features are closely related to those of other reported crystal structures of statins. The only hydrogen bond present facilitates the formation of infinite chains of mol­ecules along the b axis.     

Structural properties of a series of photochromic fluorinated indolylfulgides

Fluorinated indolyl­fulgides are a class of photochromic organic compounds that meet many of the requirements for use as optical memory media and optical switches. The X‐ray crystal structures of a series of five photochromic fluorinated indolyl­fulgides have been determined, namely (3Z)‐3‐[1‐(1,2‐di­methyl‐1H‐indol‐3‐yl)‐2,2,2‐tri­fluoro­ethyl­idene]‐4‐(1‐methyl­ethyl­idene)­dihydrofuran‐2,5‐dione (tri­fluoro­methyl­iso­propyl­idene­indolyl­fulgide), C₁₉H₁₆F₃NO₃, (I), (3Z)‐3‐[1‐(1,2‐dimethyl‐1H‐indol‐3‐yl)‐2,2,3,3,3‐penta­fluoro­propyl­idene]‐4‐(1‐methyl­ethyl­idene)­dihydrofuran‐2,5‐dione (penta­fluoro­ethyl­iso­propyl­idene­indolyl­fulgide), C₂₀H₁₆F₅NO₃, (II), (3Z)‐3‐[1‐(1,2‐di­methyl‐1H‐indol‐3‐yl)‐2,2,3,3,4,4,4‐hepta­fluoro­butyl­idene]‐4‐(1‐methyl­ethyl­idene)­dihydrofuran‐2,5‐dione (hepta­fluoro­propyl­iso­propyl­idene­indolyl­fulgide), C₂₁H₁₆F₇NO₃, (III), (3Z)‐3‐[1‐(1,2‐di­methyl‐1H‐indol‐3‐yl)‐2,2,2‐tri­fluoro­ethyl­idene]‐4‐(tri­cyclo­[3.3.1.1^3,7]­decyl­idene­)dihydrofuran‐2,5‐dione (tri­fluoro­methyl­adamantyl­idene­indolyl­fulgide), C₂₆H₂₄F₃NO₃, (IV), and (3Z)‐3‐[1‐(1,2‐di­methyl‐1H‐indol‐3‐yl)‐2,2,3,3,4,4,4‐hepta­fluoro­butyl­idene]‐4‐(tri­cyclo­[3.3.1.1^3,7]­decyl­idene­)dihydrofuran‐2,5‐dione (hepta­fluoro­propyl­adamantylidenein­dolyl­fulgide), C₂₈H₂₄F₇NO₃, (V). The photochromic property of fulgides is based on the photochemically allowed electrocyclic ring closure of a hexatriene system to form a cyclo­hexa­diene. For each fulgide examined, the bond lengths within the hexatriene system alternate between short and long, as expected. Comparing the structures of the five fulgides with each other demonstrates no significant difference in bond lengths, bond angles or dihedral angles within the hexatriene systems. The distance between the bond‐forming C atoms at each end of the hexatriene system does vary. Correlations of structural properties with optical properties are addressed.     

Four bromo‐substituted pyrazoline and isoxazolinone spiro derivatives

Conformational analyses and a structural comparison of the four spiro compounds 3‐bromo‐1,9‐di­phenyl‐4‐p‐tolyl‐7‐oxa‐1,2,8‐tri­aza­spiro­[4.4]­nona‐2,8‐dien‐6‐one, (I), C₂₄H₁₈BrN₃O₂, 3‐bromo‐4‐(4‐methoxy­phenyl)‐1,9‐di­phenyl‐7‐oxa‐1,2,8‐tri­aza­spiro­[4.4]­nona‐2,8‐dien‐6‐one, (II), C₂₄H₁₈BrN₃O₃, 3‐bromo‐4‐(4‐chloro­phenyl)‐1,7,9‐tri­phenyl‐1,2,7,8‐tetra­aza­spiro­[4.4]­nona‐2,8‐dien‐6‐one, (III), C₂₉H₂₀BrClN₄O, and 3‐bromo‐1,7,9‐tri­phenyl‐4‐p‐tolyl‐1,2,7,8‐tetra­aza­spiro­[4.4]­nona‐2,8‐di­en‐6‐one, (IV), C₃₀H_22.89Br_1.11N₄O, are presented. The mol­ecular structures are rather similar, which is as expected since the compounds are all products of concerted 1,3‐dipolar attack on (Z)‐4‐aryl­idene oxazolone and pyrazolone derivatives. The observed conformations tend to favour extended π conjugation of the benzene rings and other π systems, as shown by a comparison of selected geometric parameters of the four structures.     

Packing considerations of bis‐dimedone derivatives

We have determined the crystal structures of 2,2′‐(4‐fluoro­phenyl)­methyl­enebis(3‐hydroxy‐5,5‐di­methyl‐2‐cyclo­hexen‐1‐one), C₂₃H₂₇FO₄, (I), 2,2′‐(4‐chloro­phenyl)­methyl­enebis(3‐hy­droxy‐5,5‐dimethyl‐2‐cyclo­hexen‐1‐one), C₂₃H₂₇ClO₄, (II), 2,2′‐(4‐hydroxy­phenyl)­methyl­enebis(3‐hydroxy‐5,5‐di­methyl‐2‐cyclo­hexen‐1‐one), C₂₃H₂₈O₅, (III), 2,2′‐(4‐methyl­phenyl)­methyl­enebis(3‐hydroxy‐5,5‐di­methyl‐2‐cyclo­hexen‐1‐one), C₂₄H₃₀O₄, (IV), 2,2′‐(4‐methoxy­phenyl)­methyl­enebis(3‐hy­droxy‐5,5‐di­methyl‐2‐cyclo­hexen‐1‐one), C₂₄H₃₀O₅, (V), and 2,2′‐(4‐N,N′‐di­methyl­amino­phenyl)­methyl­enebis(3‐hydroxy‐5,5‐di­methyl‐2‐cyclo­hexen‐1‐one), C₂₅H₃₃NO₄, (VI). Structures (III) to (VI) of these bis‐dimedone derivatives show nearly the same packing pattern irrespective of the different substituent in the para position of the aromatic ring. However, (II) does not fit into this scheme, although the Cl atom is a substituent not too different from the others. The different packing of the fluoro compound, (I), can be explained by the fact that it crystallizes with two mol­ecules in the asymmetric unit, which show a different conformation of the dimedone ring. On the other hand, (I) shows a similar packing pattern to bis(2‐hydroxy‐4,4‐di­methyl‐6‐oxo‐1‐cyclo­hexenyl)­phenyl­methane, a compound containing an aromatic ring without any substituent and with Z′ = 2.     

Tri­bromo(3,5‐di­methyl‐2‐nitro­phenyl‐κ2C1,O)­tellurium(IV), bromo(3,5‐di­methyl‐2‐nitro­phenyl‐κ2C1,O)­tellurium(II) and bromo(3,5‐di­methyl‐2‐nitro­so­phenyl‐κ2C1,O)­tellurium(II)

All three title compounds, prepared from bis(3,5‐di­methyl‐2‐nitro­phenyl)­ditellurium, exhibit high degrees of intramol­ecular Te—O coordination. Their Te—O distances increase in the order C₈H₈BrNOTe < C₈H₈BrNO₂Te < C₈H₈Br₃NO₂Te, with distances of 2.165 (3), 2.306 (1) and 2.423 (6) Å, respectively, indicating that C₈H₈BrNOTe may be more aptly described as 1‐bromo‐4,6‐di­methyl‐2,1,3‐benzoxatellurazole.     

From α‐carbamoyl‐α‐cyano­oxiranes to 3‐halogenopyruv­amides

The crystal structures of the first stable α‐diol from the α‐halogenopyruv­amide series, 3‐chloro‐2,2‐di­hydroxy‐3‐phenyl­propan­amide, C₉H₁₀­ClNO₃, and three products [3‐(4‐chloro­phenyl)‐2‐cyano‐2,3‐epoxy­propan­amide, C₁₀H₇­ClN₂O₂, 3‐bromo‐2‐cyano‐2‐hydroxy‐3‐p‐tolyl­propan­amide, C₁₁H₁₁Br­N₂O₂, 3‐bromo‐2‐oxo‐3‐p‐tolyl­propan­amide, C₁₀H₁₀­BrNO₂] obtained during the systematic synthesis of α‐halogenopyruv­amides are reported. The crystal structures are dominated by hydrogen bonds involving an amide group. The stability of the geminal diol could be ascribed to hydrogen bonds which involve both hydroxyl groups.     

A silaproline‐containing dipeptide

The silaproline‐containing dipeptide N‐(3,3‐di­methyl‐1‐pivaloyl‐1‐aza‐3‐sila‐5‐cyclo­pentyl­carbonyl)‐l ‐alanine iso­propyl­amide, C₁₇H₃₃N₃O₃Si, has two independent molecules in the asymmetric unit and each adopts a β‐II folded conformation, where the amide on the terminal C interacts intramolecularly with the pivaloyl O atom. The five‐membered silaproline ring is C^β‐puckered, an infrequent conformation for the homol­ogous proline ring.     

The fungal metabolite austdiol

The title compound, (7R,8S)‐7,8‐di­hydroxy‐3,7‐di­methyl‐6‐oxo‐7,8‐di­hydro‐6H‐isochromene‐5‐carb­aldehyde, C₁₂H₁₂O₅, is a trans‐vicinal diol. Of the two fused rings, which lie approximately in the same plane, the pyran ring is almost perfectly planar, while the cyclo­hexenone ring adopts a slightly distorted half‐chair conformation. The crystal packing is dictated by two strong intermolecular O—H⃛O interactions, one involving hydroxy and keto groups, the other involving two hydroxy groups. Molecules are linked together through twofold axes, forming zigzag ribbons extended along the a axis.     

Two intermediates in the synthesis of deca­hydro­iso­quinolines with NMDA and AMPA receptor antagonist activity

In 6‐methyl‐N‐(4‐nitro­benzoyl)‐5,6‐di­hydropyridin‐2(1H)‐one, C₁₃H₁₂N₂O₄, (I), the piperidone ring is in a distorted half‐chair conformation. In 8‐methoxy‐3‐methyl‐N‐(4‐nitro­benzoyl)‐1,2,3,4,5,6,7,8‐octa­hydro­iso­quinoline‐1,6‐dione, C₁₈H₂₀N₂O₆, (II), the heterocyclic ring is in a slightly distorted half‐boat conformation, while the other six‐membered ring is in a distorted chair conformation. Compound (II) presents a strong intramolecular C—H?O hydrogen bond. In both (I) and (II), the mol­ecules interact through C—H?O interactions.     

2,4‐Di­nitro­phenyl­hydrazones of 2,4‐di­hydroxy­benz­aldehyde, 2,4‐di­hydroxy­aceto­phenone and 2,4‐di­hydroxy­benzo­phenone

In 2,4‐di­hydroxy­benz­aldehyde 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­form­amide solvate {or 4‐[(2,4‐di­nitro­phenyl)­hydrazono­methyl]­benzene‐1,3‐diol N,N‐di­methyl­form­amide solvate}, C₁₃H₁₀N₄O₆·C₃H₇NO, (X), 2,4‐di­hydroxy­aceto­phenone 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­form­am­ide solvate (or 4‐{1‐[(2,4‐di­nitro­phenyl)hydrazono]ethyl}benzene‐1,3‐diol N,N‐di­methyl­form­amide solvate), C₁₄H₁₂N₄O₆·C₃H₇NO, (XI), and 2,4‐di­hydroxy­benzo­phenone 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­acet­amide solvate (or 4‐­{[(2,4‐di­nitro­phenyl)hydrazono]phenyl­methyl}benzene‐1,3‐diol N,N‐di­methyl­acet­amide solvate), C₁₉H₁₄N₄O₆·C₄H₉NO, (XII), the molecules all lack a center of symmetry, crystallize in centrosymmetric space groups and have been observed to exhibit non‐linear optical activity. In each case, the hydrazone skeleton is fairly planar, facilitated by the presence of two intramolecular hydrogen bonds and some partial N—N double‐bond character. Each molecule is hydrogen bonded to one solvent mol­ecule.     

Three tetrahydroisoquinolinedione derivatives

N‐(2‐Chloro­benzyl)‐1,2,3,4‐tetra­hydro­iso­quinoline‐1,3‐dione, C₁₆H₁₂ClNO₂, crystallizes in P2₁/n with three crystallographically independent mol­ecules in the asymmetric unit, which differ slightly in conformation, N‐(2‐bromo‐4‐methyl­phenyl)‐1,2,3,4‐tetra­hydro­iso­quinoline‐1,3‐dione, C₁₆H₁₂BrNO₂, crystallizes in P2₁/n with one mol­ecule in the asymmetric unit andN‐(2,3‐di­chloro­phenyl)‐1,2,3,4‐tetra­hydro­iso­quinoline‐1,3‐dione, C₁₅H₉Cl₂NO₂, crystallizes in P2₁/c with one mol­ecule in the asymmetric unit. In all three structures, the heterocyclic rings adopt approximately planar conformations. The pyridine rings are orthogonal to the substituted phenyl rings. In all three structures, the crystal packing is stabilized by intermolecular C—H?O hydrogen bonds.     

[5‐Bromo‐N‐(2‐carboxylatophenyl)salicylideniminato]dimethyltin(IV)

The structure of the title di­methyl­tin(IV) complex, [2‐(5‐bromo‐2‐oxido­benzyl­idene­amino)­benzoato‐κ³O,N,O′]di­methyl­tin(IV), [Sn(CH₃)₂(C₁₄H₈BrNO₃)], features centrosymmetric dimers disposed about a central Sn₂O₂ core. Each Sn centre has seven‐coordinate pentagonal–bipyramidal geometry, taking into account two moderately long Sn—O contacts about an inversion centre [2.679 (4) and 2.981 (4) Å]. The methyl groups are in an axial orientation.     

Linkage isomerism of organoplatinum(II) compounds coordinated by two 1,3‐di­methyl­barbiturate anions

In two linkage isomers, bis[1,3‐di­methyl‐2,4,6(1H,3H,5H)‐pyrimidine­trionato]‐C⁵,O⁴‐(ethyl­enedi­amine‐N,N′)platinum(II), [Pt(C₆H₇N₂O₃)₂(C₂H₈N₂)], (I), and bis[1,3‐di­methyl‐2,4,6(1H,3H,5H)‐py­rim­idine­tri­on­ato‐C⁵](ethyl­enediamine‐N,N′)­plati­num(II) di­hyd­rate, [Pt(C₆H₇N₂O₃)₂(C₂H₈N₂)]·2H₂O, (II), crystal­lized from the same aqueous solution containing [Pt(en)(OH)₂] and 1,3‐di­methyl­barbituric acid (Hdmbarb) in a 1:2 molar ratio, a pair of monodentate dmbarb^? anions coordinate to the Pt atom at tetrahedral C atoms for (II), while one dmbarb^? anion coordinates at the carbon and the other at a deprotonated enol oxy­gen for (I). The Pt—C distances in (I) and (II) are comparable: 2.112 (4) Å for (I), and 2.114 (4) and 2.117 (4) Å for (II).     

(+)‐Gibberellin C: hydrogen‐bonding pattern of the monohydrate of a non‐racemic pentacyclic diterpenoid

In the monohydrate of the title compound, (+)‐2β,4aα‐di­hydroxy‐1,7‐di­methyl‐8‐oxo‐4bβ,7α‐gibbane‐1α,10β‐di­carb­ox­yl­ic acid‐1,4a‐lactone, C₁₉H₂₄O₆·H₂O, intermolecular hydrogen bonding progresses helically along b from carboxyl to ketone [O?O = 2.694 (5) Å]. The carboxyl and lactone carbonyl groups in translationally related mol­ecules within a helix both accept hydrogen bonds from the same water of hydration. The oxy­gen of this water in turn accepts a hydrogen bond from the hydroxyl group of a third screw‐related mol­ecule in an adjacent counterdirectionally oriented helix, yielding a complex three‐dimensional hydrogen‐bonding array. Intermolecular O?H—C close contacts were found to the carboxyl and lactone carbonyls, the hydroxyl, and the water.     

An ion pair formed by protonated Fe(cp*py)2 and the octanuclear cluster U8Cl24O4(cp*py)2 [cp*py is tetramethyl‐5‐(2‐pyridyl)cyclopentadiene]

In bis­[1,1′,2,2′,3,3′,4,4′‐octa­methyl‐5‐(2‐pyridinio)‐5′‐(2‐pyri­dyl)­ferrocene] di‐μ₃‐chloro‐hexadeca‐μ₂‐chloro‐hexa­chloro­di‐μ₄‐oxo‐di‐μ₃‐oxo‐bis­[(η⁵,κN)‐1,2,3,4‐tetra­methyl‐5‐(2‐pyridyl)­cyclo­penta­dienyl]octauranium(IV) di­chloro­methane tetrasolvate, [Fe(C₁₄H₁₇N)(C₁₄H₁₆N)]₂[U₈Cl₂₄O₄(C₁₄H₁₆N)₂]·4CH₂Cl₂, (I), two protonated Fe(cp*py)₂ units [cp*py is tetra­methyl‐5‐(2‐pyridyl)­cyclo­penta­diene] form an ion pair with the dianionic centrosymmetric cluster U₈Cl₂₄O₄(cp*py)₂. The latter is the highest nuclearity assemblage in the chemistry of uranium (non‐uranyl) compounds reported to date.     

Two new conformationally restricted 4,5‐dihydroxynorvaline analogues with a norbornane skeleton

The structures of two conformationally restricted 4,5‐di­hydroxy­norvaline analogues with a norbornane skeleton, namely methyl (1S,2S,3R,4R)‐2‐benz­amido‐3‐(1,2‐di­hydroxy­ethyl)­bi­cyclo[2.2.1]­heptane‐2‐carboxyl­ate, C₁₈H₂₃NO₅, and methyl (1R,2S,3R,4S)‐2‐benz­amido‐3‐(1,2‐di­hydroxy­ethyl)­bi­cyclo[2.2.1]­heptane‐2‐carboxyl­ate, C₁₈H₂₃NO₅, exhibit a conformation in the helical region of the ?,ψ map but their handedness is opposite. In both cases, the torsion angles (χ^1,1) giving the relative orientation of the 1,2‐di­hydroxy­ethyl group of the amino acid side chain and the benz­amide group of the peptide chain indicate that these groups adopt a nearly eclipsed conformation. Both compounds show a complex hydrogen‐bonding pattern.     

3‐Germyl‐3,3‐di­methyl­propionic acid derivatives

The crystal structures of 3,3‐di­methyl‐3‐(tri­chloro­germyl)­propionic acid, [Ge(C₅H₉O₂)Cl₃], 3,3‐di­methyl‐3‐(tri­phenyl­germyl)­propionic acid, [Ge(C₆H₅)₃(C₅H₉O₂)], and 3,3‐di­methyl‐3‐(tri‐p‐toly­lgermyl)­propionic acid, [Ge(C₇H₇)₃(C₅H₉O₂)], have slightly distorted tetrahedral geometries about the Ge atoms. All the structures form dimers via strong O—H·O hydrogen bonds, resulting in eight‐membered rings that can be best described in terms of graph‐set notation (8).