Crystal structure and Hirshfeld surface analysis of 2-benzyl-4,5-dibromo-2,3,3a,4,5,6,7,7a-octahydro-3a,6-epoxy-1H-isoindol-1-one

The title compound, C15H15Br2NO2, crystallizes with two molecules in the asymmetric unit of the unit cell. In both molecules, the tetrahydrofuran rings adopt an envelope conformation with the O atom as the flap and the pyrrolidine rings adopt an envelope conformation. In the crystal, molecules are linked by weak C—H...O hydrogen bonds, forming sheets lying parallel to the (002) plane. These sheets are connected only by weak van der Waals interactions. The most important contributions to the surface contacts are from H...H (44.6%), Br...H/H...Br (24.1%), O...H/H...O (13.5%) and C...H/H...C (11.2%) interactions, as concluded from a Hirshfeld surface analysis.

1,2-O-Isopropylidene-β-D-lyxo-furanose

In the title compound C8H14O5, the pentofuranose five-membered ring has a twisted conformation on two carbon atoms while the five-membered ring of the isopropylidene group has an envelope conformation on an oxygen atom. Hydroxy groups are involved an infinite network of O—H...O hydrogen bonds that leads to the formation of a layer parallel to the (001) plane. Only weak C—H...O contacts exist between neighboring layers.

7-Methoxypentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione

The structure of 7-methoxypentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione, C12H12O3, at 150 K has monoclinic (P21/c) symmetry. The pentacycloundecane cage compound is composed of four five-membered rings, a planar four-membered ring and a six-membered ring in a boat conformation fused into a closed strained-cage framework. All of the five-membered rings adopt an envelope conformation.

rac-(E,trans)-4-Bromo-10,10-dimethyl-9,11-dioxabicyclo[6.3.0]undec-4-ene

In the title compound, a cyclooctene ring in a twist-boat conformation and a dioxolane ring with a distorted envelope conformation are annulated in a trans configuration. Alternating strands of single enantiomers build up the crystal. Within the strands, the molecules are connected by weak C—H...O hydrogen bonds.

3-(2-Methoxyphenyl)-2,3-dihydro-1H-benzo[f]chromen-1-one

In the title compound, C20H16O3, the 2-methoxyphenyl ring is tilted by 50.67 (3)° with respect to the naphthyl ring system. The central pyran ring has an envelope conformation with the C atom bearing the pendant ring system as the flap. The methoxy group attached to the benzene ring is slightly twisted [C—C—O—C = −15.2 (1)°] from the ring. In the crystal, weak C—H...O interactions link the molecules into C(7) chains propagating along [101].

7a-Phenyltetrahydropyrrolo[2,1-b]oxazol-5(6H)-one

In the title compound, C12H13NO2, the pyrrolidinone moiety is almost flat while the oxazole ring adopts an envelope conformation with the carbon atom bearing the phenyl substituent as the flap: the angle between the mean planes of the fused heterocyclic rings is 45.47 (19)°. In the crystal, C—H...O and C—H...π contacts link the molecules into infinite [010] chains.

6,7-Dihydro-5H-pyrrolo[1,2-a]imidazole

The crystal structure of 6,7-dihydro-5H-pyrrolo[1,2-a]imidazole, C6H8N2, at 100 K has monoclinic (P21/n) symmetry. The molecule adopts an envelope conformation of the pyrrolidine ring, which might help for the relief torsion tension. The crystal cohesion is achieved by C—H...N hydrogen bonds. Interestingly, this fused ring system provides protection of the α-C atom (attached to the non-bridging N atom of the imidazole ring), which provides stability that is of interest with respect to electrochemical properties as electrolytes for fuel cells and batteries, and electrodeposition.

Conversion of diarylchalcones into 4,5-dihydropyrazole-1-carbothioamides: molecular and supramolecular structures of two precursors and three products

Chalcones of type 4-XC6H4C(O)CH=CHC6H4(OCH2CCH)-4, where X = Cl, Br or MeO, have been converted to the corresponding 4,5-dihydropyrazole-1-carbothioamides using a cyclocondensation reaction with thiosemicarbazide. The chalcones 1-(4-chlorophenyl)-3-[4-(prop-2-ynyloxy)phenyl]prop-2-en-1-one, C18H13ClO2, (I), and 1-(4-bromophenyl)-3-[4-(prop-2-ynyloxy)phenyl]prop-2-en-1-one, C18H13BrO2, (II), are isomorphous, and their molecules are linked into sheets by two independent C—H...π(arene) interactions, both involving the same aryl ring with one C—H donor approaching each face. In each of the products (RS)-3-(4-chlorophenyl)-5-[4-(prop-2-ynyloxy)phenyl]-4,5-dihydropyrazole-1-carbothioamide, C19H16ClN3OS, (IV), (RS)-3-(4-bromophenyl)-5-[4-(prop-2-ynyloxy)phenyl]-4,5-dihydropyrazole-1-carbothioamide, C19H16BrN3OS, (V), and (RS)-3-(4-methoxyphenyl)-5-[4-(prop-2-ynyloxy)phenyl]-4,5-dihydropyrazole-1-carbothioamide, C20H19N3O2S, (VI), the reduced pyrazole ring adopts an envelope conformation with the C atom bearing the 4-prop-2-ynyloxy)phenyl substituent, which occupies the axial site, displaced from the plane of the four ring atoms. Compounds (IV) and (V) are isomorphous and their molecules are linked into chains of edge-fused rings by a combination of N—H...S and C—H...S hydrogen bonds. The molecules of (VI) are linked into sheets by a combination of N—H...S, N—H...N and C—H...π(arene) hydrogen bonds. Comparisons are made with the structures of some related compounds.

(3S,5R,6S)-Diphenylmethyl 1-oxo-6-bromopenicillanate

In the title compound, C21H20BrNO4S, a key intermediate in the synthesis of the widely used β-lactamase inhibitor tazobactam, the five-membered thiazolidine ring adopts an envelope conformation and the four-membered azetidine ring is in a distorted planar conformation. The crystal structure features C—H...O hydrogen bonds and a weak C—H...π interaction.

3-(2,5-Dichlorothiophen-3-yl)-5-(2,4-dimethoxyphenyl)-1-methyl-4,5-dihydro-1H-pyrazole

In the title compound, C16H16Cl2N2O2S, the pyrazole ring has an envelope conformation with the C atom bearing the phenyl ring being the flap. The dihedral angles between the central pyrazole ring (all atoms) and pendant thiophene and phenyl rings are 2.00 (14) and 81.49 (12)°, respectively. In the crystal, weak C—H...O, Cl...π and π–π stacking interactions link the molecules into a three-dimensional network.