10‐(4‐Fluorophenyl)‐3,3,6,6,9‐pentamethyl‐3,4,6,7,9,10‐hexahydroacridine‐1,8(2H,5H)‐dione and 10‐(4‐fluorophenyl)‐3,3,6,6‐tetramethyl‐9‐­propyl‐3,4,6,7,9,10‐hexahydroacridine‐1,8(2H,5H)‐dione

10‐(4‐Fluoro­phenyl)‐3,3,6,6,9‐penta­methyl‐3,4,6,7,9,10‐hexa­hydro­acridine‐1,8(2H,5H)‐dione, C₂₄H₂₈FNO₂, (I), crystallizes with two crystallographically independent mol­ecules (which differ slightly in conformation), while 10‐(4‐fluoro­phenyl)‐9‐propyl‐3,3,6,6‐tetra­methyl‐3,4,6,7,9,10‐hexa­hydro­acridine‐1,8(2H,5H)‐dione, C₂₆H₃₂FNO₂, (II), crystallizes with one mol­ecule per asymmetric unit. In both structures, the central ring in the acridine moiety is in a sofa conformation, while the outer rings adopt intermediate half‐chair/sofa conformations. The central pyridine ring is orthogonal to the substituted phenyl ring. In both structures, the packing of the crystal is stabilized by C—H?O intermolecular hydrogen bonds.     

3‐Methyl 5‐isopropyl 2‐methoxy­imino­methyl‐6‐methyl‐4‐(3‐nitro­phenyl)‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate

The crystal structure of the title compound, C₂₀H₂₃N₃O₇, consists of relatively isolated mol­ecules. The substituted 1,4‐di­hydro­pyridine ring adopts a flattened boat conformation. Both ester groups, at positions 3 and 5, have cis,cis geometry. The phenyl ring is nearly planar and is approximately perpendicular to the 1,4‐di­hydro­pyridine ring (dihedral angle 87.70°).     

Methyl 4‐(2‐chloro‐5‐nitro­phenyl)‐2,7,7‐tri­methyl‐5‐oxo‐1,4,5,6,7,8‐hexa­hydro­quinoline‐3‐carboxyl­ate

The title compound, C₂₀H₂₁ClN₂O₅, has potential calcium modulatory properties. The 1,4‐di­hydro­pyridine ring has the usual shallow boat conformation. The 2‐chloro‐5‐nitro­phenyl ring is oriented such that the chloro substituent is in a synperiplanar orientation with respect to the 1,4‐di­hydro­pyridine ring plane, while the nitro substituent sits over the 1,4‐di­hydro­pyridine ring. The cyclo­hexenone ring has a conformation that is approximately half‐way between that of an envelope and that of a half‐chair. The mol­ecules are linked into chains by intermolecular N—H⋯O hydrogen bonds.     

6‐(3,4‐Di­fluoro­benzoyl)‐3‐[2‐(4‐pyridyl)­ethyl]‐1,3‐benzo­thia­zol‐2(3H)‐one

A new type of benzo­thia­zolinone derivative with potential pharmacological activity, viz. 6‐(3,4‐di­fluoro­benzoyl)‐3‐[2‐(4‐pyridyl)­ethyl]‐1,3‐benzo­thia­zol‐2(3H)‐one, C₂₁H₁₄F₂N₂O₂S, has been prepared and studied by NMR, IR and single‐crystal X‐ray diffraction techniques. The mol­ecule is not planar, the pyridine and di­fluoro­benzene moieties being located above and below the benzo­thia­zole ring system. The carbonyl O atoms are involved in an intramolecular hydrogen‐bond‐type interaction.     

(±)‐Methyl and (±)‐ethyl 4‐(2,3‐di­fluoro­phen­yl)‐2,6,6‐trimethyl‐5‐oxo‐1,4,5,6,7,8‐hexa­hydro­quinoline‐3‐carboxyl­ate

The title compounds, C₂₀H₂₁F₂NO₃ and C₂₁H₂₃F₂NO₃, respectively, belong to a class of 1,4‐dihydro­pyridines whose members sometimes display calcium modulatory properties. The 1,4‐dihydro­pyridine rings have the usual shallow boat conformation. In each structure, the 2,3‐difluoro­phenyl ring is oriented such that the fluoro substituents are in a synperi­planar orientation with respect to the 1,4‐dihydro­pyridine ring plane and the oxocyclo­hexene ring has a slightly distorted envelope conformation. Both structures exhibit the same inter­molecular N—H⋯O hydrogen‐bonding motif, in which the mol­ecules are linked into chains by inter­actions involving the carbonyl O atom of the oxocyclo­hexene ring.     

2‐Nitroso‐1,3‐diphenyl‐1,2,3,4‐tetrahydrobenzo[b][1,6]naphthyridine

The title compound, C₂₄H₁₉N₃O, crystallizes in the centrosymmetric space group P2₁/a with one mol­ecule in the asymmetric unit. The tetra­hydro­pyridine ring has a boat conformation. The dihedral angle between the fused pyridine rings is 16.2 (1)°. The equatorial and axial orientations of the two phenyl groups with respect to the tetra­hydro­pyridine ring are confirmed. The nitroso group is coplanar with the attached C—N—C group. The interplanar angle formed between the fused tetra­hydro­pyridine and benzene planes is 13.4 (1)°. The crystal packing is stabilized by an intermolecular C—H⃛O hydrogen bond, which forms a C(9) graph‐set chain running along the [001] direction.     

1H‐Pyrrolo[2,3‐b]pyridine‐3‐acetic acid as a molecular probe for use in auxin physiology

The structural characterization of 1H‐pyrrolo­[2,3‐b]­pyridine‐3‐acetic acid (alternative name: 7‐aza­indole‐3‐acetic acid), C₉H₈N₂O₂, reveals similar molecular geometry, i.e. with the side chain perpendicular to the 7‐aza­indole ring, to that of the natural plant growth hormone indole‐3‐acetic acid (auxin) and its alkyl­ated and halogenated derivatives.     

A highly functionalized ferrocenyl­pyrazolo­[2,3‐a]­pyridine

The crystal structure of [2‐(4‐bromo­phenyl)‐4‐cyano‐5‐ferrocenyl­pyrazolo­[2,3‐a]­pyridin‐7‐yl]­aceto­nitrile, C₂₆H₁₇N₄FeBr or [Fe(C₅H₅)(C₂₁H₁₂BrN₄)], shows that the pyrazolo­pyridine ring system (PP), the bromo­phenyl ring (BP) and the cyclo­penta­diene ring (Cp) are nearly planar. The PP ring system is twisted out of the plane of the BP and Cp rings by about 20°.     

Methyl (SR)‐10‐chloro‐1,2,3,4,5,6‐hexahydro‐6‐hydroxy‐8‐methoxy‐1‐methyl‐1,9‐phenanthroline‐6‐carboxylate

In the title compound, C₁₆H₁₉ClN₂O₄, the pyridine ring is nearly planar, the piperidine ring is non‐planar and the cyclo­hexane ring adopts a screw‐boat conformation. The carboxyl­ate group makes a dihedral angle of 80.9 (2)° with the least‐squares plane through the cyclo­hexane ring.     

Cocrystals of diastereoisomers of 1,4‐dihydro­pyridine derivatives

A mixture of the RR/SS and RS/SR diastereoisomeric pairs of methyl 4‐(2,4‐dichloro­phen­yl)‐2,7‐dimethyl‐5‐oxo‐1,4,5,6,7,8‐hexa­hydro­quinoline‐3‐carboxyl­ate, C₁₉H₁₉Cl₂NO₃, forms cocrystals in which there is one unique mol­ecule in the asymmetric unit, but the mol­ecule displays disorder in the region of the 7‐position of the quinoline ring system as a result of the random occurrence of the diastereoisomers at the same crystallographic site. A similar arrangement exists in the monohydrate cocrystals that form from a mixture of the RR/SS and RS/SR diastereoisomeric pairs of methyl 4‐(2,4‐dichloro­phen­yl)‐2‐methyl‐7‐phenyl‐5‐oxo‐1,4,5,6,7,8‐hexa­hydro­quinoline‐3‐carboxyl­ate monohydrate, C₂₄H₂₁Cl₂NO₃·H₂O. These compounds belong to a class of 1,4‐dihydro­pyridines whose members have calcium modulatory properties. The 1,4‐dihydro­pyridine rings have the usual shallow boat conformation. In each structure, the 2,4‐dichloro­phenyl ring is oriented such that the 2‐chloro substituent is in a synperi­planar orientation with respect to the 1,4‐dihydro­pyridine ring plane. In each crystal structure, the mol­ecules are linked into chains by N—H⋯O hydrogen‐bonding inter­actions.     

4‐(4‐Fluoro‐3‐phenoxy­phen­yl)‐6‐(4‐fluoro­phen­yl)‐2‐oxo‐1,2‐dihydro­pyridine‐3‐carbonitrile and the 6‐(4‐methyl­phen­yl)‐ analogue

The crystal structures of the title compounds, viz. C₂₄H₁₄F₂N₂O₂, (I), and C₂₅H₁₇FN₂O₂, (II), respectively, have been determined in order to unravel the role of an ordered F atom in generating stable supra­molecular assemblies. On changing the substitution from fluorine to a methyl group, C—H⋯F inter­actions are replaced by C—H⋯π inter­actions, revealing the importance of such weak inter­actions when present alongside N—H⋯O and C—H⋯O hydrogen bonds. The dihedral angle between the planes of the 4‐fluoro­phenyl ring and the pyridine ring is 26.8 (1)° in (I), while that between the planes of the 4‐methyl­phenyl and pyridine rings is 29.5 (1)° in (II).     

N,N‐Diethyl‐2,6,6‐trimethyl‐4‐(3‐nitrophenyl)‐5‐oxo‐1,4,5,6,7,8‐hexahydroquinoline‐3‐carboxamide

The title compound, C₂₃H₂₉N₃O₄, has potential calcium modulatory properties. The conformation of the 1,4‐di­hydro­pyridine ring is unusual in that it is planar, instead of the usual shallow boat. The 3‐nitro­phenyl substituent is in the synperiplanar orientation with respect to the di­hydro­pyridine ring plane. The oxo­cyclo­hexene ring has a distorted envelope conformation, with the out‐of‐plane atom being disordered on opposite sides of the ring plane. The mol­ecules are linked into chains by intermolecular hydrogen bonds.     

4‐[N,N‐Bis(2‐cyano­ethyl)­amino]­pyridine

The title compound, 3,3′‐(4‐pyridyl­imino)­di­propane­nitrile, C₁₁H₁₂N₄, has a twofold axis and consists of a pyridine ring head and two cyano­ethyl tails, the three groups being linked by an N atom. The planar geometry around the amino N atom suggests conjugation with the π‐system of the pyridine ring. The mol­ecules are stacked in a layer structure via relatively weak to very weak intermolecular C—H⃛π and C—H⃛N hydrogen‐bond interactions.     

trans‐(2‐Acetylpyridine‐κ2N,O)dichlorobis(dimethyl sulfoxide‐κS)ruthenium(II)

In the title complex, [RuCl₂(C₇H₇NO)(C₂H₆OS)₂], the metal ion is at the centre of a distorted octahedral NOCl₂S₂ coordination sphere. The neutral 2‐acetyl­pyridine ligand binds to the metal ion through the pyridine N and carbonyl O atoms, forming a five‐membered chelate ring. The monodentate S‐coordinating di­methyl sulfoxide mol­ecules are mutually cis, and the two remaining positions in the coordination sphere are occupied by two mutually trans Cl^? ions.     

fac‐Tri­carbonyl(4,4′‐di­methyl‐2,2′‐bi­pyridine)­tri­phenyl­tin(II)­rhenium(I)

The title organometallic compound, fac‐tri­carbonyl‐2κ³C‐(4,4′‐di­methyl‐2,2′‐bi­pyridine)‐2κ²N,N′‐tri­phenyl‐1κ³C¹‐tin(II)­rhenium(I)(Sn—Re), [ReSn(C₆H₅)₃(C₁₂H₁₂N₂)(CO)₃], con­tains three unique π–π stacking interactions. The result is an infinite chain of uninterrupted alternating intra‐ and intermolecular offset π–π stacking interactions throughout the crystal lattice. This extended π–π stacking arrangement, and an additional isolated intramolecular π–π interaction between the remaining 4,4′‐di­methyl‐2,2′‐bi­pyridine ring and a second phenyl group, impose geometric constraints on the Re and Sn atoms, yielding distorted octahedral and tetrahedral coordinations, respectively, for the metal centers.     

3,5‐Di­fluoro‐4‐nitro­pyridine N‐oxide and 3,5‐di­amino‐4‐nitro­pyridine N‐oxide monohydrate

The mol­ecule of 3,5‐di­fluoro‐4‐nitro­pyridine N‐oxide, C₅H₂F₂N₂O₃, is twisted around the C—NO₂ bond by 38.5 (1)°, while the 3,5‐di­amino analogue, 3,5‐di­amino‐4‐nitro­pyridine N‐oxide monohydrate, C₅H₆N₄O₃·H₂O, adopts a planar conformation stabilized by intramolecular hydrogen bonds, with a significant redistribution of π electrons.     

Three methoxy‐substituted diethyl 4‐­phenyl‐2,6‐di­methyl‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate compounds

Diethyl 4‐(2,5‐di­methoxy­phenyl)‐2,6‐di­methyl‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate, C₂₁H₂₇NO₆, (I), diethyl 4‐(3,4‐di­methoxy­phenyl)‐2,6‐di­methyl‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate, C₂₁H₂₇NO₆, (II), and diethyl 2,6‐di­methyl‐4‐(3,4,5‐tri­methoxy­phenyl)‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate, C₂₂H₂₉NO₇, (III), crystallize with hydrogen‐bonding networks involving the H atom bonded to the N atom of the 1,4‐di­hydro­pyridine ring and carbonyl O atoms in (I) and (II). Unusually, (III) shows O atoms of methoxy groups serving as hydrogen‐bond acceptors.     

Two carbamoyl‐substituted di­hydro­pyrimidines: potential mimics of di­hydro­pyridine calcium channel blockers

The structures of two conformationally similar 1,4‐di­hydro­pyrimidines with a novel carbamoyl substitution, viz. 6‐methyl‐5‐(N‐methyl­carbamoyl)‐4‐phenyl‐1,2,3,4‐tetrahydro­py­rimidine‐2‐thione monohydrate, C₁₃H₁₅N₃OS·H₂O, (I), and 4‐(4‐chloro­phenyl)‐6‐methyl‐5‐(N‐methyl­carbamoyl)‐1,2,3,4‐tetra­hydro­pyrimidine‐2‐thione monohydrate, C₁₃H₁₄ClN₃OS·H₂O, (II), exhibit the structural features of 1,4‐di­hydro­pyridine calcium channel blockers. In both structures, the pyrimidine ring adopts a flattened boat conformation and the carbamoyl side chain is in an extended conformation with an anticlinal orientation. The phenyl ring occupies a pseudo‐axial position with respect to the pyrimidine ring in these structures. Both compounds crystallize with one mol­ecule of water, which participates in a two‐dimensional hydrogen‐bonding network. The mol­ecules are linked into dimers by N—H·S hydrogen bonds in both structures.     

2‐(6‐Bromo­pyridin‐2‐yl)‐6‐methyl‐[1,3,6,2]­diox­aza­borocane,a new stable (pyridin‐2‐yl)­boronic acid derivative

The crystal structure of the first reported non‐substituted N‐methyl­diox­aza­borocane confirms that the presence of a methyl group attached to the N atom introduces an NB bond length that is longer than that in a simple diox­aza­borocane ring. The presence of more N atoms in the vicinity of the B atom in the title compound [systematic name: 6a‐(6‐bromo­pyridin‐2‐yl)‐3a‐methyl‐2,3,4,5‐tetra­hydro‐1,6‐dioxa‐3a‐aza‐6a‐borapentalene], C₁₀H₁₄BBrN₂O₂, does not modify significantly any structural parameter in the diox­aza­borocane ring. On the other hand, a small asymmetry appears in the bond angles of the pyridine C atom next to the B atom.     

(Z)‐7‐Chloro‐3‐[(3‐chloro­phenyl)­methyl­idene]‐4‐p‐tosyl‐3,4‐di­hydro‐2H‐1,4‐benzoxazine

In the title compound, C₂₂H₁₇Cl₂NO₃S, the mol­ecule is a substituted 3,4‐di­hydro‐2H‐1,4‐benzoxazine compound which has three phenyl rings which are essentially planar. The 3,4‐di­hydro‐2H‐oxazine part of the mol­ecule is fused to the benzo ring and has a half‐boat conformation; the dihedral angle between the planar part of the oxazine ring and the benzo ring is 10.2 (2)°. The (3‐chloro­phenyl)­methyl­idene substituent has a Z configuration in relation to the ring N atom of the oxazine moiety. Interestingly, the p‐toluenesulfonyl (p‐tosyl) substituent on the ring N atom protrudes away from the 3‐­chloro­phenyl substituent thus avoiding any steric interaction.