Remaining Ring Atoms Research Articles

The X-ray Structures of 2,4-Dibromothiazole and 2,4-Diacetyl-5-bromothiazole

2,4-Dibromothiazole [orthorhombic, a = 6.700 (10), b = 16.21 (3), c = 5.516 (8) A, space group Fmm2] shows a disordered crystal structure with molecules randomly oriented with respect to the direction of the Br–C(2)–N–C(2)–Br unit and the remaining ring atoms S(3) and C(3)H showing mixed occupancy. 2,4-Diacetyl-5-bromothiazole [triclinic, a = 4.040 (2), b = 8.254 (5), c = 13.208 (8) A, α = 96.191 (17), β = 93.865 (16), γ = 94.067 (11)°, space group P-1] shows a structure dominated by halogen bonding, intramolecular between 4-COMe and 5-Br and intermolecular between 2-COMe of one molecule and 5-Br of the next. 2,4-Dibromothiazole is disordered in the crystal structure with molecules randomly oriented either way round as shown. There is evidence for unusual intramolecular, and perhaps also intermolecular, halogen bonding between Br and C = O in the structure of 2,4-diacetyl-5-bromothiazole.

Crystal structure of ethyl 2-cyano-3-[(1-eth-oxy-ethyl-idene)amino]-5-(3-meth-oxy-phen-yl)-7-methyl-5H-1,3-thia-zolo[3,2-a]pyrimidine-6-carboxyl-ate.

In the title compound, C22H24N4O4S, the central pyrimidine ring adopts a sofa conformation with the ring-junction N atom displaced by 0.2358 (6) Å from the mean plane of the remaining ring atoms. The 3-meth­oxy­phenyl ring, at the chiral C atom opposite the other N atom, is positioned axially and is inclined to the thia­zolo­pyrimidine ring with a dihedral angle of 83.88 (7)°. The thia­zole ring is essentially planar (r.m.s. deviation = 0.0034 Å). In the crystal, pairs of weak C—H⋯O hydrogen bonds link mol­ecules related by twofold rotation axes to form R 2 2(8) rings, which in turn are linked by weak C—H⋯N inter­actions, forming ribbons along [-110]. In addition, π–π stacking inter­actions [centroid—centroid distance = 3.5744 (15) Å] connect the ribbons, forming slabs lying parallel to (001).

Crystal structure of [(2R,3R,4S)-3,4-bis(acet-yloxy)-5-iodo-3,4-di-hydro-2H-pyran-2-yl]methyl acetate.

In the title compound, C12H15IO7, the 3,4-di­hydro-2H-pyran ring is in a distorted half-boat conformation with the atom bearing the acet­yloxy group adjacent to the C atom bearing the methyl­acetate group lying 0.633 (6) Å above the plane of the remaining ring atoms (r.m.s. deviation = 0.0907 Å). In the crystal, mol­ecules are linked into a supra­molecular chain along the a axis through two C—H⋯O inter­actions to the same acceptor carbonyl O atom; these chains pack with no specific inter­molecular inter­actions between them.

Ethyl 1′-methyl-2-oxo-4′-[(3aR,5R,5aS,8aS,8bR)-2,2,7,7-tetramethyltetrahydro-3aH-bis[1,3]dioxolo[4,5-b:4′,5′-d]pyran-5-yl]-2H-spiro[acenaphthylene-1,2′-pyrrolidine]-3′-carboxylate

In the title mol­ecule, C30H35NO8, the ace­naphthyl­enone moiety, two atoms of a methyl pyrrolidine ring (N and C atoms) and four atoms of an ethyl acetate moiety (two C and two O atoms) are disordered over two sets of sites in ratio 0.532 (7):0.468 (7). The three C atoms of a di­meth­oxy­ethane ring and dioxolane ring attached with two methyl groups are disordered over two sets of sites in 0.66 (2):0.34 (2) and 0.62 (2):0.38 (2) ratios, respectively. The major and minor components of the ace­naphthyl­ene ring are essentially planar (r.m.s. deviations = 0.0254 and 0.0436 Å, respectively). The major and minor components of the pyrrolidine ring adopt C-envelope conformations with C atoms displaced by 0.492 (11) and 0.595 (7) Å from the remaining ring atoms. One of the dioxolane rings is disordered with its major component in an envelope conformation [C displaced by 0.511 (11) Å] and the minor fraction is more or less planar with an r.m.s. deviation of 0.070 Å. The other dioxolane ring is in an envelope conformation, with a C atom displaced by 0.438 (3) Å from the remainder of the ring atoms. The crystal packing features C—H⋯O inter­actions, which generate C(9) chains.

(2S,3S)-3-(3-Bromophenyl)-6,6-dimethyl-2-nitro-2,3,6,7-tetrahydrobenzofuran-4(5H)-one

The title compound, C16H16BrNO4, has two adjacent chiral C atoms and both have an S configuration. The fused cyclo­hex-2-enone and di­hydro­furan rings both adopt envelope conformations, with the quaternary C atom and the nitro-substituted C atoms as the respective flap. The flap atoms lie 0.607 (3) and −0.253 (2) Å, respectively, from the mean plane of the remaining ring atoms on opposite sides. The dihedral angle between the mean plane of the four coplanar atoms of the di­hydro­furan ring and the phenyl ring is 86.16 (3)°. In the crystal, mol­ecules are linked by weak C—H⋯O inter­actions, forming a ladder motif parallel to the b axis.

14-Methoxy-4,6-dimethyl-9-phenyl-8,12-dioxa-4,6-diazatetracyclo[8.8.0.02,7.013,18]octadeca-2(7),13,15,17-tetraene-3,5,11-trione

The title compound, C23H20N2O6, crystallizes with two mol­ecules in the asymmetric unit in which the dihedral angles between the mean planes of the pyran and phenyl rings are 66.6 (1) and 61.9 (1) °. The fused pyrone and pyran rings each adopts a sofa conformation. In the crystal, C—H⋯O hydrogen bonds link the mol­ecules, forming a two-dimensional network parallel to [001].

14-Ethoxy-4,6,9-trimethyl-8,12-dioxa-4,6-diazatetracyclo[8.8.0.02,7.013,18]octadeca-2(7),13,15,17-tetraene-3,5,11-trione

In the title compound, C19H20N2O6, the pyrone and pyran rings adopt envelope conformations with the same common C atom as the flap, the dihedral angle between the planes of the remaining ring atoms being 68.27 (4)°. The planar atoms of the pyran ring and the diaza­cyclic ring are almost coplanar, the dihedral angle between their mean planes being 3.29 (7)°. Moreover, the planar atoms of the pyrone ring and benzene ring of the coumarin unit are also close to coplanar, the dihedral angle between their mean planes being 8.03 (9)°. The meth­oxy group lies in the plane of the benzene ring, with a dihedral angle between their mean planes of 9.4 (2)°. In the crystal, the molecules are linked by C—H⋯O hydrogen bonds resulting in sheets of mol­ecules in the ac plane.

8,8-Dimethyl-8,9-dihydro-7H-chromeno[2,3-b]quinoline-10,12-dione.

In the title compound, C18H15NO3, the fused benzopyran and pyridine rings are essentially coplanar [r.m.s. deviation = 0.0533 Å with a maximum deviation of 0.080 (1) Å for a benzene C atom]. The cyclo­hexa­none ring adopts an envelope conformation with the dimethyl-substituted C atom 0.660 (2) Å out of the plane formed by the remaining ring atoms (r.m.s. deviation = 0.0305 Å). The dihedral angle between the mean planes of the pyran and cyclo­hexa­none rings is 12.95 (6)°. In the crystal, mol­ecules are linked via C—H⋯O hydrogen bonds, leading to chains running along [011].

A triclinic polymorph of methyl (3R,3′S)-1′,1′′-dimethyl-2,2′′-dioxodispiro[indoline-3,2′-pyrrolidine-3′,3′′-indoline]-4′-carboxylate

In the title compound, C22H21N3O4, the central pyrrolidine ring adopts a C-envelope conformation with a C atom 0.6593 (13) Å displaced from the mean plane formed by the remaining ring atoms. The indoline ring systems (r.m.s. devisations of 0.0356 and 0.0547 Å) are almost perpendicular to the mean plane of the pyrrolidine ring, making dihedral angles of 89.7 (6) and 82.5 (6)°. The acetate group attached to the pyrrolidine ring assumes an extended conformation. In the crystal,N—H⋯O and C—H⋯O hydrogen bonds connect adjacent molecules, forming an infinite tape extending along [1-1-1]. The crystal packing is further consolidated by strong π–π inter­actions with a centroid–centroid distance of 3.2585 (8) Å. The title compound is a polymorph of previously reported monoclinic structure [Ganesh et al. (2012 ▶). Acta Cryst. E68, o2902–o2903].

4′-Methyl-1H-14′,19′-dioxa-4′-azaspiro[indole-3,5′-tetracyclo[18.4.0.02,6.08,13]tetracosane]-1′(24′),8′,10′,12′,20′,22′-hexaene-2,7′(3H)-dione

In the title compound, C29H28N2O4, the indoline ring system is essentially planar, with a maximum deviation of 0.027 (2) Å; the carbonyl O atom lies 0.102 (1) Å out of the least-squares plane of the indole ring. The pyrrolidine ring adopts a C-envelope conformation, with a C atom displaced by 0.643 (2) Å from the mean plane formed by the remaining ring atoms. The pyrrolidine ring makes a dihedral angle of 86.1 (8)° with the indoline ring system. In the crystal, N—H⋯O hydrogen bonds result in the formation of cyclic centrosymmetric dimers [R 2 2(8)]. C—H⋯π inter­actions also occur, leading to a chain along the b-axis direction. There is a rather weak π–π electron inter­action between the pyrrazole and benzene rings, with a centroid–centroid distance of 3.765 (1) Å.

4′-Methyl-14′,19′-dioxa-4′-azaspiro[acenaphthylene-1,5′-tetracyclo[18.4.0.02,6.08,13]tetracosane]-1′(24′),8′,10′,12′,20′,22′-hexaene-2,7′(1H)-dione

In the title compound, C33H29NO4, the acenaphthyl­ene ring system is essentially planar (r.m.s. deviation = 0.0290 Å). The pyrrolidine ring adopts a C-envelope conformation with a C atom displaced by 0.671 (2) Å from the mean-plane formed by the remaining ring atoms. The pyrrolidine ring is fused to acenaphthyl­ene ring system making a dihedral angle of 88.0 (7)°. In the crystal, mol­ecules are linked into R 2 2(9) dimers via C—H⋯N and C—H⋯O hydrogen bonds. Two C atoms act as donors to the same O atom acceptor, resulting in the formation of R 2 1(7) ring motifs. These two motifs combine to form hydrogen-bonded sheets running along the a- and b-axis directions.

11-Hydroxy-9-[1-(4-methylphenyl)-4-oxo-3-phenylazetidin-2-yl]-18-oxo-10-oxa-2-azapentacyclo[9.7.0.01,8.02,6.012,17]octadeca-12,14,16-triene-8-carbonitrile

In the title compound, C33H29N3O5, the four-membered ring of the β-lactam fragment is essentially planar (r.m.s. deviation = 0.0122 Å), with the carbonyl O atom displaced from this ring by 0.856 (9) Å. The mean planes of the meth­oxy­phenyl and phenyl rings are inclined at dihedral angles 85.10 (7) and 21.56 (14)°, respectively, with respect to the mean plane of the four-membered ring. The pyrrolidine rings adopt envelope conformations with C atoms lying 0.535 (4) and 0.519 (4) Å out of the planes formed by the remaining ring atoms. The furan ring also adopts an envelope conformation with a C atom 0.560 (3) Å out of the plane formed by the remaining ring atoms. The nine-membered indene ring is almost planar (r.m.s. deviation = 0.0240 Å), with the carbonyl O atom displaced by 0.145 (3) Å from this ring. The mol­ecular structure is stabilized by a strong intra­molecular O—H⋯N hydrogen bond and the crystal structure is consolidated by C—H⋯O hydrogen bonds.

2-(3,4-Dimethyl-5,5-dioxo-2H,4H-pyrazolo[4,3-c][1,2]benzothiazin-2-yl)-N-(3-methoxybenzyl)acetamide

The asymmetric unit of the title compound, C21H22N4O4S, contains two mol­ecules (A and B), in which the thia­zine rings adopt an S-envelope conformation with the S atoms displaced by 0.621 (2) and 0.697 (2) Å from the mean planes formed by the remaining ring atoms. The dihedral angles between the N-methyl­acetamide groups and the meth­oxy­benzene rings are 8.67 (10) and 54.49 (6)° in the two mol­ecules and the equivalent torsion angles in the N-methyl­acetamide chains connecting the ring systems also differ. In the crystal, N—H⋯O hydrogen bonds connect the components into C(4) [100] chains of alternating A and B mol­ecules. The packing is consolidated by weak C—H⋯O inter­actions, which generate a three-dimensional network.

Ethyl 2-(3,4-dimethyl-5,5-dioxo-1H,4H-benzo[e]pyrazolo[4,3-c][1,2]thiazin-1-yl)acetate

In the title mol­ecule, C15H17N3O4S, the heterocyclic thia­zine ring adopts a twist-boat conformation, which differs from that in related compounds, with adjacent S and C atoms displaced by 0.981 (4) and 0.413 (5) Å, respectively, on the same side of the mean plane formed by the remaining ring atoms. The mean plane of the benzene ring makes a dihedral angle of 23.43 (14)° with the mean plane of the pyrazole ring. In the crystal, mol­ecules are connected by weak C—H⋯O hydrogen bonds to form a three-dimensional network. The H atoms of the methyl group attached to the pyrazole ring were refined over six sites with equal occupancies.

Ethyl 3-ethoxycarbonylmethyl-7-methyl-5-phenyl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylate

In the title compound, C20H22N2O4S, the central pyrimidine ring incorporating a chiral C atom is significantly puckered and adopts a slight boat conformation with C atom bearing the phenyl ring and the N atom opposite displaced by 0.367 (2) and 0.107 (2) Å, respectively, from the plane formed by the remaining ring atoms. The benzene ring is positioned axially to the pyrimidine ring, making a dihedral angle of 88.99 (5)°. The thia­zole ring is essentially planar (r.m.s. deviation = 0.0033 Å). In the crystal, pairs of C—H⋯O inter­actions result in centrosymmetric dimers with graph-set motifs R 1 2(7) and R 2 2(8). A weak C—H⋯π contact is also observed.

4-Methyl-3-phenyl-2,4-dihydropyrazolo[4,3-c][1,2]benzothiazine 5,5-dioxide

In the title mol­ecule, C16H13N3O2S, the heterocyclic thia­zine ring adopts a twist chair conformation with the S atom and an adjacent C atom displaced by 0.946 (5) and 0.405 (6) Å, respectively, on the same side of the mean plane formed by the remaining ring atoms. The mean planes of the benzene rings make dihedral angles of 16.61 (10) and 15.32 (10)° with the mean plane of the pyrazole ring. The mol­ecular structure is consolidated by intra­molecular C—H⋯N inter­actions and the crystal packing is stabilized by N—H⋯O and C—H⋯N hydrogen bonds. The crystal studied was an inversion twin with the refined ratio of the twin components being 0.53 (11):0.47 (11).

2-(3,4-Dimethyl-5,5-dioxo-2H,4H-pyrazolo[4,3-c][1,2]benzothiazin-2-yl)-N-(2-fluorobenzyl)acetamide

In the title mol­ecule, C20H19FN4O3S, the heterocyclic thia­zine ring adopts a half-chair conformation with the S atom displaced by 0.668 (4) Å from the mean plane formed by the remaining ring atoms. The mean planes of the benzene and pyrazole rings are inclined with respect to each other at a dihedral angle of 17.4 (3)°. The acetamide chain (O/N/C/C/C) linking the pyrazole and 2-fluoro­benzyl rings is essentially planar (r.m.s. deviation = 0.030 Å) and forms dihedral angles with the mean planes of these rings of 78.8 (2) and 78.89 (14)°, respectively. The crystal structure is stabilized by N—H⋯O and C—H⋯O hydrogen-bonding inter­actions, resulting in a six-membered ring with an R 2 1(6) motif, while C—H⋯O and C—H⋯F hydrogen-bonding inter­actions result in chains of mol­ecules lying along the c axis in a zigzag fashion.

5-Hydroxy-6-[(E)-2-phenylethenyl]-5,6-dihydro-2H-pyran-2-one isolated fromGoniothalamus ridleyi

In the title compound, C13H12O3, the pyran ring adopts a half-chair conformation with a C atom deviating from the least-squares plane of the remaining ring atoms by 0.606 (2) Å. This plane and that of the benzene ring make a dihedral angle of 44.18 (6)°. In the crystal, mol­ecules are linked through O—H⋯O hydrogen bonds into infinite chains along the b axis, and these chains are cross-linked by C—H⋯O hydrogen bonded into sheets lying parallel to the bc plane. The layers are further connected via C—H⋯π inter­actions to form a three-dimensional supra­molecular structure.

N-Benzyl-4-hydroxy-2-methyl-1,1-dioxo-2H-1λ6,2-benzothiazine-3-carboxamide

In the title mol­ecule, C17H16N2O4S, the heterocyclic thia­zine ring adopts a half-chair conformation, with the S and N atoms displaced by 0.546 (4) and 0.281 (4) Å, respectively, on opposite sides of the mean plane formed by the remaining ring atoms. The mol­ecular structure is stabilized by an intra­molecular O—H⋯O hydrogen bond. The two aromatic rings are inclined to one another by 42.32 (11)°. In the crystal, mol­ecules are linked by pairs of N—H⋯O hydrogen bonds, forming inversion dimers. The dimers are linked via a series of C—H⋯O inter­actions, leading to the formation of a three-dimensional network.

2-(3,4-Dimethyl-5,5-dioxo-2H,4H-pyrazolo[4,3-c][1,2]benzothiazin-2-yl)acetic acid

In the title mol­ecule, C13H13N3O4S, the heterocyclic thia­zine ring adopts a half-chair conformation in which the S and an adjacent C atom are displaced by 0.919 (3) and 0.300 (4) Å, respectively, on the same side of the mean plane formed by the remaining ring atoms. The mean planes of the benzene and pyrazole rings are inclined at a dihedral angle of 18.32 (12)° with respect to each other. The acetate group is oriented at 80.75 (8)° with respect to the pyrazole ring. The crystal structure is stabilized by O—H⋯N and C—H⋯O hydrogen bonds, resulting in fused eight- and seven-membered rings with R 2 2(8) and R 2 2(7) graph-set motifs, respectively.